1.

The area of the parallelogram whose adjacent sides are given by a = 3i - j+2k and 5 =i+49-6 is[Note: Area of the parallelogram is axba) 614 sq unitsb) 614 sq unitsc) 573 unitsd) 32 units​

Answer»

GIVEN :

\bf \overrightarrow{a} = 3 \hat{i} -  \hat{j} + 2 \hat{k} and \bf \overrightarrow{b} =  \hat{i}+ 4 \hat{j} -6 \hat{k} are adjacent SIDES of PARALLELOGRAM .

TO FIND :

• Area of parallelogram = ?

SOLUTION :

• We KNOW that area of parallelogram is –

\bf  \implies \large{ \boxed{ \bf Area =| \overrightarrow{a} \times \overrightarrow{b}|}}

\bf  \implies  Area =|(3 \hat{i} -  \hat{j} + 2 \hat{k} )\times ( \hat{i}+ 4 \hat{j} -6 \hat{k})|

\bf  \implies  Area = \left|\begin{array}{ccc}\bf\hat{i} & \bf\hat{j}& \bf\hat{k} \\ \\\bf3& \bf - 1& \bf2 \\  \\\bf1& \bf 4& \bf - 6\end{array}\right|

\bf  \implies  Area =|\hat{i} \{ ( - 1)( - 6) - (4)(2)\} -\hat{j} \{ (3)( - 6) - (4)(2)\}  + \hat{k} \{ ( 4)(3) - (1)( - 1)\}|

\bf  \implies  Area =|\hat{i} \{6 - 8\} -\hat{j} \{ - 18- 8\}  + \hat{k} \{12 -( - 1)\}|

\bf  \implies  Area =|\hat{i} \{ - 2\} -\hat{j} \{ -26\}  + \hat{k} \{12  + 1\}|

\bf  \implies  Area = |- 2\hat{i}  + 26\hat{j}+13 \hat{k}|

\bf  \implies  Area = \sqrt{ {( - 2)}^{2} +  {(26)}^{2} +  {(13)}^{2} }

\bf  \implies  Area = \sqrt{4+  676+169}

\bf  \implies  Area = \sqrt{849} \:\:sq.\:\: units

\bf  \implies {\boxed{ \bf Area = 29.14 \:\:sq.\:\: units}}



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