JEE Main 2016 · 10 Apr · Shift 1 · Mathematics Q89

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MathematicsSingle correct+4 / -1Question 89 of 90

The angle of elevation of the top of a vertical tower from a point A, due east of it is 45°. The angle of elevation of the top of the same tower from a point B, due south of A is 30°. If the distance between A and B is $54\sqrt2$ m, then the height of the tower (in metres), is :

36\sqrt3

54\sqrt3

108

Answer and worked solution

Official answer: B

A is h from the foot of the tower (45°), and B is $h\sqrt3$ from it (30°). The foot, A and B form a right angle at A, so $3h^2=h^2+(54\sqrt2)^2$ and h = 54 m.

Topics:Heights and distances

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JEE Main 2016 · 10 Apr · Shift 1, Mathematics question 89