Question : Two points A and B are on the ground and on opposite sides of a tower. A is closer to the foot of the tower by 42 m than B. If the angles of elevation of the top of the tower, as observed from A and B are 60° and 45°, respectively, then the height of the tower is closest to:
Option 1: 87.6 m
Option 2: 98.6 m
Option 3: 88.2 m
Option 4: 99.4 m
Correct Answer: 99.4 m
Solution : PQ is a tower and let AQ be $x$ m and BQ = $x + 42$ In $\triangle APQ$ $\tan 60° = \frac{PQ}{AQ}$ ⇒ $\sqrt3 = \frac{PQ}{x}$ ⇒ $PQ = \sqrt3 x$.....................................(1) In $\triangle PBQ$ $\tan 45° = \frac{PQ}{QB}$ ⇒ $1 = \frac{PQ}{x + 42}$ ⇒ $PQ = (x + 42)$......................................(2) From equation (1) and equation (2) ⇒ $\sqrt3x = x + 42$ ⇒ $x (\sqrt3 - 1) = 42$ ⇒ $x = \frac{42}{(\sqrt3 - 1)}$ ⇒ $x = \frac{42}{(\sqrt3 - 1)} \times \frac{(\sqrt3 + 1)}{(\sqrt3 + 1)}$ = $\frac{42 (1.732 + 1)}{(3 - 1)}$ = $21 \times 2.732 \approx 57.4$ From equation (2) PQ = 57.4 + 42 = 99.4 m Hence, the correct answer is 99.4 m.
Result | Eligibility | Application | Selection Process | Cutoff | Admit Card | Preparation Tips
Question : The angles of elevation of the top of a tower from two points on the ground at distances 32 m and 18 m from its base and in the same straight line with it are complementary. The height (in m) of the tower is____________.
Question : A pole of length 7 m is fixed vertically on the top of a tower. The angle of elevation of the top of the pole observed from a point on the ground is 60° and the angle of depression of the same point on the ground from the top of the tower is 45°. The height (in m) of
Question : From the top of house A in a street, the angles of elevation and depression of the top and foot of another house B on the opposite side of the street are 60° and 45°, respectively. If the height of house A is 36 m, then what is the height of house B? (Your answer
Question : From two points on the ground and lying in a straight line through the foot of a pillar, the two angles of elevation of the top of the pillar are complementary. If the distances of the two points from the foot of the pillar are 12 metres and 27 metres and the two points lie on
Question : The angles of elevation of a pole from two points which are 75 m and 48 m away from its base are $\alpha$ and $\beta$, respectively. If $\alpha$ and $\beta$ are complementary, then the height of the tower is:
Regular exam updates, QnA, Predictors, College Applications & E-books now on your Mobile