Area Formulas and Parallelograms

Rectangle Area of a rectangle = bh b = base h = height

Square Area of a square = s2, s = side

Example 1: Find the area of the following figures. 15 5 10 (–5, 4) (2, 4) (2, –3) (–5, –3) (0,0) 25 8 10 14 20

Example 2: a. Find the area of a square whose side is 9 b. Find the area of a square whose diagonal is 18 c. Find the side of a square whose area is 64 d. Find the perimeter of a square whose area is 100 e. Find the area of a square whose perimeter is 64

Example 3: Find the area of the shaded region. (Assume right angles) 20 12 28 40

11.2 Parallelograms Area of a Parallelogram Theorem 100 The area of a parallelogram is equal to the product of the base and the height. A = bh where b is the length of the base and h is the height.

Area of a Triangle Theorem 101 The area of a triangle is equal to one-half the product of a base and the height (or altitude) for that base. A∆ = 1/2bh where b is the base of the triangle and h is the altitude.

Example 1: Find the total area of each figure. (In each figure the triangle is mounted on a rectangle.) 6 13 5 12 5 8

Example 2: Find the base of a parallelogram of height 18 and area of 252.

Example 3: Find the area of the obtuse triangle. 24 60º 5

Now you try! Solve for x.