An aircraft is flying at a constant height with a speed of 360 km/h. From a point on the ground, the angle of elevation of the aircraft at an instant was observed to be 45°. After 20 seconds, the angle of elevation was observed to be 30°. Determine the height at which the aircraft is flying (use $\sqrt{3}$ = 1.732).

If a kite is flying at a height of $40\sqrt{3}$ meters from the level ground, attached to a string inclined at 60° to the horizontal, then the length of the string is

1. 80 m

2. $60 \sqrt{3}$ m

3. $80\sqrt{3}$ m

4. 120 m.

A ladder 14 m long rests against a wall. If the foot of ladder is 7 m from the wall, then the angle of elevation is

1. 15°

2. 30°

3. 45°

4. 60°

If a pole 6 m high casts shadow $2\sqrt{3}$ m long on the ground, then the sun's elevation is

1. 60°

2. 45°

3. 30°

4. 90°