Section 1.7
Recall that perimeter is the distance around a figure, circumference is the distance around a circle, and area is the amount of surface covered by a figure. Perimeter and circumference are measured in units of length. Area is measured in square units.
Formulas for Perimeter P, Area A, and Circumference C
1.Square with side s P = 4s A = s 2 2.Rectangle with length l and width w P = 2 l + 2w A = l w
3.Triangle with side lengths a, b, and c, base b and height h P = a + b + c 4.Circle. with diameter d and radius r P = d = 2 r A = r 2
The in-bounds portion of a singles tennis court is shown. Find its perimeter and area. P = 2 l + 2wA = l w = 2(78) + 2(27)= (78)(27) = = 2106 ft 2 = 210 ft. Example 1
The smallest circle on an Olympic target is 12 centimeters in diameter. Find the circumference and area of the smallest circle to two decimal places. Use = C = dA = r 2 = (3.14)(12)= (3.14)(6 2 ) = cm= (3.14)(36) = cm 2 Example 2
Triangle JKL has vertices J(1, 6), K(6, 6) and L(3, 2). Find the perimeter of triangle JKL. Example 3
The base of a triangle is 24 feet. Its area is 216 square feet. Find the height of the triangle. Example 4