Find the angle of elevation of the sun's altitude when the height of shadow of a vertical pole is equal to its height.
(a) 30° (b) 60° (c) 45° (d) 90°
In Fig. 9.74, what are the angles of depressions of the top and bottom of a pole from the top of a tower h m high.
(a) 45°, 70° (b) 45°, 60° (c) 45°, 30° (d) 45°, 45°
The angle of elevation of the top of a tower from a point on the grounds which is 30 m away from the foot of the tower is 30°. The height of the tower is
(a) 10 m (b) (c) (d) 30 m
A ladder leaning against a wall makes an angle of 60° with the horizontal. If the foot of the ladder is 2.5 m away from the wall, find the length of the ladder.
Let AB be the ladder and CA be the wall.
Given: BC = 2.5 m, ∠ABC = 60°
AB = 5 cm and ∠BAC = 30°
From Pythagoras Theorem, we have
AB2 = BC2 + CA2
52 = (2.5)2 + (CA)2
(CA)2 = 25 – 6.25 = 18.75 m
Hence, length of the ladder is