The values of the cosine function are represented by the axis OX of the goniometric circumference (circumference centered at the origin and of radius 1). Therefore the cosine is zero for the 90º and 270º angles.
1. The formula for calculate the perimeter of a rectangle, is:
P=2L+2W
P is the perimeter of the rectangle (P=320 feet). L is the lenght of the rectangle. W is the width of the rectangle. <span> 2. The problem says that the length of the rectangle is three times the width, so you have: </span> L=3W
3. When you substitute L=3W and P=320, into P=2L+2W, you obtain:
