Zach has a rectangular living room that measures 10 feet wide by 20 feet long. He's thought about bringing in some furniture, but he doesn't want to spoil the perfect rectangularness of it. In order to cover the floor of his living room with carpet, how many square feet of carpet does Zach need?
Answer
The area of the living room is A = lw where l is length and w is width. Evaluate lw for l = 10 and w = 20. We get 200 square feet.
Example 2
Zach has a rectangular living room that measures 10 feet wide by 20 feet long. How much trim will Zach need if he wants to put trim all around the edge of the floor?
Answer
The perimeter of the living room is P = 2l + 2w. Evaluate for l = 10 and w = 20. That gives us P = 20 + 40 = 60 feet of trim.
Example 3
What is the area of the triangle shown below? No fair guessing. We know what a lucky guesser you are.
Answer
Use the formula , where A is the area of the triangle, b is the length of the base, and h is the height.
Evaluate the formula for b = 5 and h = 2 to find that square inches.
, where A is the area of the triangle, b is the length of the base, and h is the height. 
square inches.