## Algebra: A Combined Approach (4th Edition)

a. The formula for the area of a trapezoid is A = $\frac{1}{2}(b_{1} +b_{2})h$. Substituting the values for the length and width into the equation, we get A = $\frac{1}{2}(24 +56)12$ Solve the equation for A by simplifying: A = $\frac{1}{2}(80)12$ A = 40(12) A = 480 The perimeter is found by adding each side. The equation is: P = 24 + 20 + 56 + 20 P = 120 b. The amount of framing needed is the perimeter, because it is the length surrounding the picture. The amount of glass needed is the area, because it must cover the area of the picture.