# 1.7 Introduction to Perimeter, Circumference, & Area Geometry.

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1.7 Introduction to Perimeter, Circumference, & Area Geometry

Terminology Perimeter –The total distance (sum of side lengths) around a geometric figure. Circumference –The total distance around the curvature of a circle. Area –The total two dimensional space contained within the boundaries of a geometric figure.

Rectangle Perimeter P=2 l +2 w Area A= lw l (length) W (width)

Square Perimeter P=4s Area A=s 2 S (side)

Triangle Perimeter P=a+b+c Area A= ½ bh b (base) h (height) ac

Circle Diameter d=2r Circumference C=2πr Area A=πr 2 diameter r a d i u s ** Always use the π button on the calculator; even when the directions say to use 3.14.

Example: Find the perim. & area of the figure. P=2 l +2 w P=2(5in)+2(3in) P=10in+6in P=16in A= lw A=(5in)(3in) A=15in 2 3 in 5 in

Ex: Find the perim. & area of the figure. P=4s P=4(20m) P=80m A=s 2 A=(20m) 2 A=400m 2 20 m

Ex: Find the perim. & area of the figure. P=a+b+c P=5ft+7ft+6ft P=18 ft A= ½ bh A= ½ (7ft)(4ft) A= ½ (28ft 2 ) A= 14ft 2 7 ft 5 ft 4 ft 6 ft

Ex: Find the circumference & area of the circle. C=2πr C=2π(5in) C=10π in C≈31.4 in A=πr 2 A=π(5in) 2 A=25π in 2 A≈78.5 in 2 1 0 i n

More Practice Problems Solve the area of a square that has a perimeter of 24 meters.

More Practice Problems If a circle has a circumference of 100 yards, then what is its area?

More Practice Problems You are planning a deck along two sides of a pool. The pool measures 18 feet by 12 feet. The deck is to be 8 feet wide. What is the area of the deck?

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