The angle of elevation of an aeroplane as observed from a point 30 m above the transparent water-surface of a lake is 30° and the angle of depression of the image of the aeroplane in the water of the lake is 60°. The height of the aeroplane from the water-surface of the lake is

A hydrogen filled balloon ascending at the rate of 18 kmph was drifted by wind. Its angle of elevation at 10th and 15th minutes were found to be 60° and 45° respectively. The wind speed (in whole numbers) during the last five minutes, approximately, is equal to

If x = cosecθ - sinθ and y = secθ - cosθ, then the relation between x and y is

The distance between two pillars is 120 metres. The height of one pillar is thrice the other. The angles of elevation of their tops from the midpoint of the line connecting their feet are complementary to each other. The height (in metres) of the taller pillar is (Use : √3 = 1.732)

If cosθ = x²-y²/x²+y² then the value of cotθ is equal to [ If 0 ≤  θ ≤ 90⁰]

The value of the expression 2(sin6θ+cos6θ)-3(sin4θ+cos4θ)+1 is