This section includes 7 InterviewSolutions, each offering curated multiple-choice questions to sharpen your Current Affairs knowledge and support exam preparation. Choose a topic below to get started.
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48. The angle of elevation of the top of a building from the foot of the tower is 30 and theangle of elevation of the top of the tower from the foot of the building is 45°. If the toweris 30 m high, find the height of the building. CBSE2015-3M |
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| 2. |
V3दा: 4: 300 मी. की दूरी से क्षेतिज तल पर स्थित किसी शिखर की चोटी का उन्नयन कोण (का/of elevation) 30% है। शिखर की ऊँचाई ज्ञात करें। g |
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| 3. |
(1) Prove that V6 is an irrational number. |
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Answer» Suppose we consider, √6 is a rational number . Then we can express it in the form of a/b ∴√6 = a/b, where a and b are positive integer and they are co-prime, i.e.HCF(a,b) = 1 ∴√6 = a/b =>b√6 = a =>(b√6)² = a² [squaring both sides] =>6b² = a²………..(1) Here, a² is divided by 6 ∴ a is also divided by 6. [we know that if p divides a², then p divides a] ∴ 6|a =>a = 6c [c∈ℤ] =>a² = (6c)² =>6b² = 36c² [from (1)] =>b² = 6c² Here, b² is divided by 6, ∴ b is also divided by 6. ∴ 6|a and 6|b we observe that a and b have at least 6 as a common factor. But this contradicts that “a and b are co-prime.” It means that our consideration of “√6 is a rational number” is not true. Hence, √6 is an irrational number. I would use the proof by contradiction method for this. So let's assume that the square root of 6 is rational. By definition, that means there are two integers a and b with no common divisors where: a/b = square root of 6. So let's multiply both sides by themselves: (a/b)(a/b) = (square root of 6)(square root of 6)a2/b2= 6a2= 6b2 But this last statement means the RHS (right hand side) is even, because it is a product of integers and one of those integers (at least) is even. So a2must be even. But any odd number times itself is odd, so if a2is even, then a is even. Since a is even, there is some integer c that is half of a, or in other words: 2c = a. Now let's replace a with 2c: a2= 6b2(2c)2= (2)(3)b22c2= 3b2 But now we can argue the same thing for b, because the LHS is even, so the RHS must be even and that means b is even. Now this is the contradiction: if a is even and b is even, then they have a common divisor (2). Then our initial assumption must be false, so the square root of 6 cannot be rational. |
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| 4. |
न. 1 g 1- 27 xX'+—% 9A afilr-b न 3 |
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| 5. |
Case ACase ( A |
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| 6. |
ttureWhat is the importance of default case in switch case st |
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Answer» The switch and case keywords evaluate expression and execute any statement associated with constant expression whose value matches the initial expression. If there is no match with a constant expression, the statement associated with the default keyword is executed. |
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13. Arun is treating his friends for his birthday. Four ofhis friends opt for ice creams that cost 12 each andfive of his friendschoose a juice costing8 each. How muchmoney did Arunspend on the treat? |
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Answer» 96 rupees only for the treatment Total money= 12*4+5*8= 48+4088 thanks why did india opt for planning |
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| 8. |
beh is 2a-7a + 5 less than a* - 3a+2a - 3? |
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Answer» Your correct answer isa³-5a²+9a-8 |
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| 9. |
: Show that(3A. (11Asinsin+sinA. (7A= sin 2A-sin 5Aion: |
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Answer» sin(A/2).sin(7A/2) + sin(3A/2)sin(11A/2) =(1/2) [ 2sin(7A/2).sin(A/2) + 2sin(11A/2)sin(3A/2) ] =(1/2) [{ cos( 7A/2 - A/2) - cos( 7A/2 + A/2) } + { cos( 11A/2 - 3A/2)- cos( 11A/2 + 3A/2) } ( using formula, product to sum) =(1/2) [ ( cos3A - cos4A ) + (cos4A - cos7A) ] =(1/2) [ cos3A - cos7A ] =(1/2) 2 sin[(7A - 3A)/2 ] sin[(7A+3A)/2 ] ( using formula, sum to product) = sin2A sin5A ( Proved) |
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| 10. |
integration root x dx |
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Answer» ∫√x .dx=(x^3/2)×(2/3) |
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| 11. |
A chord of a circle of radius 14 cm subtends an angle of 60 at the ceFind the area of the corresponding minor segment of the circle.(Use π , 22 and V3-1-73)7 |
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Answer» AB is the Chord. Radii drawn from points A & B are making 90 degrees at the center of the circle. Thus ∆AOB is a right angl triangle with height and base both equal to radius ‘r’. = 14 cm Area of the small segment.(Green Area) = Total are covered by sector AoB – Area of the triangle AOB. Area of the sector AOB = (ᶿ/360) ∏*r^2 Since ᶿ = 90 Area of the sector AOB = (90/360) 22*14*14/7 = 154 Square cm Area of the Triangle AOB = height * base / 2 = 14 * 14 / 2 = 98 Square cm. Area of the small segment.(Green Area) = 154 – 98 = 56 Square cm. Area of the big segment = Area of the circle - Area of the small segment.(Green Area) = 22*14*14/7 – 56 = 316 – 56 = 260 Square cm. |
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| 12. |
remainder.Rohit distributes toffees to his friends on his birthday. if he gives 5, 10 and12 to each, he is left with no toffees. What is the least number of toffees heshould buy ? |
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Answer» least number of toffees he should buy= lcm of three number5=1×510=2×512=2×2×3lcm=2×2×3×5=60 |
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| 13. |
integration of root x |
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| 14. |
Maria and Kenya equally shared one-fourthof a pie that was left over. What fraction ofthe original pie did each friend get? Usethe picture to help you. |
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| 15. |
09To find width of the river, a man observes the top of a tower on the opposite bankmaking an angle of elevation of 61°. When he moves 50 m backward from bank andobserves the same top of the tower his line of vision makes an angle of elevation 35%Find the height of the tower and width of the river. (tan 61° 1.8, tan 35 0.7)i) |
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Answer» So, height of tower is 63.64 m and width of river is 31.82m. |
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| 16. |
25Activity (1): There are some real numberswritten on a card sheet. Use these numbersand construct two examples each ofaddition, subtraction, multiplication anddivision. Solve these examples.(-32Activity (II):Start4 V6+10 J6+ V3X35465+5End |
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Answer» uper side is this is 1st activity answer and down side is 2nd activity answer |
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| 17. |
1=Integral(x*asin(x), x) |
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| 18. |
1. A man observes the top of a tower at an angle of elevation 30 viewed at the distanceI-30meter from the foot of the tower. Calculate the height of the tower |
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Answer» let the height of the tower be hthen tan 30°=h/30h=30/√3=10√3m |
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| 19. |
acos x-bsin xbcosx+asin xtan x>1 |
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| 20. |
The factors of 1-81a2 are1) (1 + 9a)(1 - 9a)3) (a + 9)(a 9) |
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Answer» 1-81a²using identity a²-b²= 1-(9a²) = (1-9a) (1+9a) |
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| 21. |
-Iftan 2A = cot (A-21), where 2A is an acute angle then find theCase zoecnalue of A |
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| 22. |
29. Prove that CoS A + sin A-1tcot using the identity cosee?A -cot2 A 1. 5 |
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Answer» Like if you find it useful |
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| 23. |
©+ :6(A) 194(C) 198(B) 190(D) 200 |
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Answer» 200 may be the answer c) is correct answer a) is the correct answer a) the correct answer |
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| 24. |
12. If a, b, c are the three positive integers, which of the following is true for+cb |
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Answer» b) a²+b²= c² is correct |
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| 25. |
In how many ways can I invite one or more of six friends to a dinner? |
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Answer» He can invite one or more friends by inviting 1 friend, or 2 friends or 3 friends, or all the 6 friends. 1 friend can be selected out of 6 in 6C1 = 6 ways 2 friends can be selected out of 6 in 6C2 = 15 ways 3 friends can be selected out of 6 in 6C3 = 20 ways 4 friends can be selected out of 6 in 6C4 = 15 ways 5 friends can be selected out of 6 in 6C5 = 6 ways 6 friends can be selected out of 6 in 6C6 = 1 ways Therefore the required number of ways (combinations) = 6 + 15 + 20 + 15 + 6 + 1 = 63 |
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| 26. |
Exercise 7.81. Lata distributes 64 toffees equally among her 8 friends. How many toffeesdoes each friend get? |
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Answer» Each student will get64/8= 8 toffee sthanks |
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| 27. |
- एक दुकानदार ने 200 अंकित मूल्य की मेज क्रमिक 10% और15% की छूट पर खरीदी। उसने मेज की ढुलाई पर 7 खर्च किएऔर मेज को 208 में बेच दिया। उसका लाभ प्रतिशत ज्ञातकीजिए? |
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Answer» 200*10/100=20200-20=180180*15/100=27180-27=153153+7=160208-160=148148/200*100=74profit=74% profit is 74% I agree that I copied discount = 200×10%= 200×10/100= 201st time cp = 200-20=180again he got 15% discountdiscount= 180×15/100= 27cp = 180-27= 153carrying charge= 7cp = 153+7=160sp = 208profit= 208-160=48%profit = profit ×100/cp = 48×100/160 = 30% |
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| 28. |
Valueof (2 +1(2-1)'sA) 1982(C) 198(B) 3024(D) 200 |
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| 29. |
. Find the value of 3 tan-3 cosee64° |
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Answer» Tan(26°)=cot(90-26) = cot(64°)so 3tan^2(26)=3cot^2(64)so 3tan^2(26)–3cosec^2(64) can be written as3cot^2(64)–3cosec^2(64)= 3[cot^2(64)–cosec^2(64)] = 3(-1) = -3the answer is -3 |
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¢ __L.__-J-‘sin'(180°+A). tand 360°-A). . »5 [Senimt ,,.LL;LM_L,_“,“\J” 180°2A). o Ao8t (904 A) cosee” A sin(180°=A)g |
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Answer» sin(180+ A)= -sinAtan(360-A)= -tanAsec(180-A)= -sec Acos(90+A)= sinAnow-sin^3A*(-tanA)(sec^2A)/sin^2A*1/sin^2A*sinA = tan^3A |
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| 31. |
m1 - 10) writerore:sin A1 + COS A-sin A2 cosee A.1 + COSAsin A1+cos A |
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Answer» sinx/ 1 + cosx + 1+ cosx/ sinx = sinx( 1 + cosx)^2/sinx( 1+ cosx) = . = sinx^2 + 1+ cosx^2+2cosx_/ sinx( 1+ cosx) = = 1 + 1 + 2cosx/sinx(1+ cosx) = 2 (1+ cosx)/ sinx( 1 + cosx)= = 2/ sinx = 2cosecx |
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round table cover has six equal designs as shownin Fig. 12.14. If the radius of the cover is 28 cm, findthe cost of making the designs at the rate ofき0.35 per cm? (Use V3 = 1.7) |
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Answer» thank u sorry ,I cant understand near by #area of designs = 6 ×????? |
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| 33. |
From the top of tower, 100m high, a man observes two cars on the opposite sidesof the tower with the angles of depression 30' and 45' respectively. Find thedistance between the cars. (Use v3 1.73) |
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| 34. |
Around table cover has six equal designs as shownin Fig. 12.14. If the radius of the cover is 28 cm, findthe cost of making the designs at the rate of0.35 per cm. (Use V3 = 1.7)13. |
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| 35. |
Arun began business with 4500 and was joined afterwards by Kumar with 3000. Hanslong Kumar's capital used in the business if the profits at the end of the year were divided inthe ratio of 2:1?(1) 7 month (2) 9 month (3) 3 month (4) 4 month (5) of these |
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Answer» My answer is 9months solution Ohhh simple ratio bee nai nikalna aata hai Let B invested money for x months.4500 * 12 : 3000 * x = 2/1540/30x = 2/1540 = 60xx = 9 months. the answer is 9 month...... 9 month is the answer the correct answer is 9 month my answer is 9 month the answer is 9 months |
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| 36. |
3 wrilleh as mixed fra(b) 4 |
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Answer» Please hit the like button if this helped you |
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| 37. |
17. For all positive integers n, show that-1" 2户+ |
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Answer» thanks |
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| 38. |
1. Natural and Whole Numbers (Sp aget fra) |
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Answer» Natural numbers are the set of positive integers, that is, integers from 1 to ∞ excluding fractional n decimal part. They are whole numbers excluding zero. Natural Numbers are also called counting numbers. Zero is the only whole number which is not a natural number. |
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| 39. |
Prove that 2 to thepower n is greaterthan n for allpositive integers n. |
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| 40. |
3. Problem: Show that 49" +16n -1 is divisible by 64 for all positive integers n. |
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Answer» OK, I'm assuming anyone reading this will be familiar with the concept a mod b... If you're not, a mod b is the remainder you'd get dividing a by b. I'm going to use = for "congruent to" here... What this boils down to proving is that: 49^n + 16n = 1 mod 64 Let's start with the easy stuff... Power of 49 49^n mod 640 11 492 333 174 1 WELL! Now, THAT simplifies things a lot, doesn't it? The index of 49 mod 64 is merely 4... Thus, for all n, let n = a mod 4. Then, we can say that 49^n = 49^a mod 64. OK, now all we have to do is get this 16 n thing in there... When you do that, you get: 49^n mod 64 49^ n + 16n mod 641 149 49 + 16 = 6533 33 + 32 = 6517 17 + 48 = 651 1 + 64 = 65 In all of these cases, subtract 1 and you get 64... |
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| 41. |
If a and b are positive integers such that Npositive integer, then N is(a + ib)-107i is a198200190208 |
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Answer» thnqqqqqqq |
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| 42. |
No three positive integers a, b, and c satisfy the equation a^{n}+b^{n}=c^{n} for any integer value of n greater than 2. Is thistrue? |
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| 43. |
cos Asin A +1cos A F sin A-1= cosec A + cot A, using the identity cosee A-1 + cot AsO. 'r/ |
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| 44. |
... New amount=0100kercise 9AExpress the following as perc(11) 100(1) 100following as a fra |
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Answer» (i) 9/100=0.09(ii)14/100=0.14The answer is correct. 9/100 Final result : 9/100 = 0.09 (1)9percent(2)14pecent |
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| 45. |
(i*x)*asin(sin(12)) |
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Answer» sin^-1{sinx}=x; iff x is in proper limits we have to check wether x is in its proper limit i.e. -π/2<=x<=π/2Now,let nπ<x<(n+1)π let,x=(n+1)π-y {iff x is more near to (n+1)π}x=nπ+y {iff x is more near to nπ} since difference b/w max and min value of x is π so range of y is given by: 0<y<π/2 So, (n+1)π-x = y; is clearly in its proper limits[ since : 0<y<π/2] Now, 3π<12<4π sin12=-sin(4π-12)=sin(12–4π) {sin(2nπ-x)=-sinx} Therefore, sin^-1{(sin12)} = sin^-1{sin(12–4π)}=12–4π [ sin^-1{sinx}=x ; iff x is in proper limits] sin^-1(sin12)=Sin^-1sin12=12 |
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| 46. |
How many cubic metres of earth must be dug out to sink a well which is 16 m deep and which has a radius of3.5 m? Ifthe earth taken out is spread over a rectangular plot of dimensions 25 mx16 m, what is the height of10. |
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| 47. |
3. F15.(i) 34+32+30+...+10 |
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Answer» 10+....+30+32+34 = (2+4+...+34)-(2+4+6+8) = 17/2(4+32) - 20 = 17*18 - 20 = 306 - 20 = 286 |
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| 48. |
4 Find the mean of the following distribution:x: 10 12 20 25 35f 3 10 15 7 5 |
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| 49. |
Example 10. Si |
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Answer» a^7/10*b^1y^-8/5÷a^-1/8b^5/4y^-5a^7/10+1/8*b^1-5/4*y^-8/5+5=a^56+10/80*b^4-5/4*y^-8+25/5=a^66/10*b^-1/4*y^17/5a^33/5*b^-1/4*y^17/5 |
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| 50. |
Example 10: Show that 5-3 is irrational. |
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Answer» Let us assume that5-√3 is rational. Let ,5 -√3 = r , where "r" is rational 5 - r =√3 Here,LHS is purely rational.But,on the other hand ,RHS is irrational.This leads to a contradiction.Hence,5-√3 is irrational |
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