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On a similar concept, a radio station tower was built in two sections A and B. Tower is supported by wires from a point. Distance between the base of the tower and point O is 36 m. From point O, the angle of elevation of the top of section B is 300 and the angle of elevation of the top of section A is 450. What is the height of the section B? (a) 12√3 m(b) 12√2 m (c) 8√3 m (d) 4√2 m1(ii)What is the height of the section A? (a) 12(2-√2)m(b) 24(2 - √2) m(c) 12(3-√3)m(d) 12(3 - √3) m1(iii)What is the length of the wire structure from the point O to the top of section A ? (a) 32√2 m(b) 24√3 m (c) 28√3 m (d) 36√2 m1(iv)What is the length of the wire structure from the point O to the top of section B ? (a) 12√3 m(b) 24√3 m (c) 28√3 m (d) 16√3 m1(v)What is the angle of depression from top of tower to point O ? (a) 300(b) 450 (c) 150 (d) 750 |
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Answer» Given : Tower is in two SECTIONS section B then above that section A Distance between base of tower and point O is 36 m From point O , ANGLE of elevation of the top of section B is 30° From point O , angle of elevation of the top of section A is 45° To Find : height of the section B (a) 12√3 m (b) 12√2 m (c) 8√3 m (d) 4√2 m height of the section A (a) 12(2-√2)m (b) 24(2 - √2) m (c) 12(3-√3)m (d) 12(3 - √3) m length of the wire structure from the point O to the top of section A (a) 32√2 m (b) 24√3 m (c) 28√3 m (d) 36√2 m length of the wire structure from the point O to the top of section B (a) 12√3 m (b) 24√3 m (c) 28√3 m (d) 16√3 m angle of depression from top of tower to point O (a) 30° (b) 45° (c) 15° (d) 75° Solution: height of the section B Tan 30° = height of the section B / 36 => 1/√3 = height of the section B / 36 => height of the section B = 36/√3 => height of the section B = 12√3 height of the section A Tan 45° = (height of the section A + height of the section B) / 36 => 1 = (height of the section A + 12√3) / 36 => height of the section A = 36 - 12√3 = 12( 3- √3) length of the wire structure from the point O to the top of section A => COS45 = 36/Wire length to the top of section A => 1/√2 = 36/Wire length to the top of section A => wire length to the top of section A = 36√2 length of the wire structure from the point O to the top of section B => cos30 = 36/Wire length to the top of section B => √3/2 = 36/Wire length to the top of section B => wire length to the top of section A = 24√3 angle of depression from top of tower to point O = 45° as angle of depression = angle of elevation Learn More: The angle of elevation of the top of a tower at any point A on the ... A TV. tower stands vertically on the side of a road. A boy observed ... |
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