Activity 2. Solve the following problems using inverse trigonometric functions. 1. The lower edge of a picture is 4 ft., the upper edge is 9 ft above the eye of an observer. At what horizontal distance should he stand if the angle subtended by the picture is a maximum? An isosceles triangle has legs 10 cm. The base decreases at the rate of 4 cm/sec. Find the rate of change of the angle at the apex when the base is 16 cm. A ladder 14 ft long is leaning against a fence 8 ft high, with the upper end projecting over the fence. If the lower end slides away from the fence at the rate of 2 ft/sec, find the rate at which the angle between the ladder and the ground is changing when the upper end is just at the top of the fence