Answer
a. Area = 480 square inches, Perimeter = 120 inches
b. The frame has to do with perimeter, and the glass has to do with area.
Work Step by Step
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.