Use the area of a polygon to justify why 144 is a perfect square.

The angle of depression would be 26.57°

Step-by-step explanation: Please refer to the attached picture for further details.

What harry has done has effectively led to the formation of a right angled triangle. As shown in the diagram, the camera has been mounted at a height of 8 feet above the ground. Also he mounts the camera at a horizontal from the entrance, which puts the camera at 16 feet away from the entrance (not from the ground). In order to capture every movement at the entrance, the camera range would be determined by an angle which covers everything from top to bottom of the entrance. That gives you the angle of depression which is at the point labelled CAMERA in the triangle.

Having determined two sides and an angle (unknown) in a right angled triangle, we shall use the trigonometric ratios as follows;

Tan ∅ = Opposite/Adjacent

Where the opposite is 8 (side facing the reference angle) and the adjacent is 16 (side that lies between the reference angle and the 90 degree angle)

Tan ∅ = 8/16

Tan ∅ = 0.5

By use of a calculator,

∅ = 26.5650

∅ ≈ 26.57

Therefore the angle of depression of the surveillance camera should be 26.57°