Perimeter & Area
Mathematics, Grade 8
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A = 1 2 h (b 1 + b 2) A = 1 2 4 (5 + 8 ) 3.14 (4 )2 = A = 1 2 b • h A = 1 2 (9 )(6 ) = A = Triangle Trapezoid Circle Perimeter Area • Perimeter is the distance around a figure. • Area is the number of square units inside the boundary of a two-dimensional figure. • The area of a triangle is one-half of the base length times the height. • The area of a circle is times the square of the radius. • The area of a trapezoid is one-half the height (h) times the sum of the base lengths b 1 and b 2. • To find the perimeter, add all side lengths. or substitute 12 for b and 8 for h. P = 9 + 10 + 2 + 7 + 3 + 4 + 2 + 2 + 2 + 5 = 46 units P = 8 + 8 + 12 + 12 = 40 units P = 2 (12) + 2 (8) P = 2 b + 2 h = 24 + 16 y x (-4, -2) (-4, 3) (4, 3) (4, -2) 10 8 12 9 2 2 2 2 4 3 7 5 = 40 units Rectangle Rectangle base (b) height (h) A = b • h = 8 • 5 = 40 units2 A = b • h = 8 • 5 = 40 units2 Parallelogram • If a triangular section is cut and placed on the opposite side of a parallelogram, it forms a rectangle. • Therefore, a parallelogram has the same area as a rectangle with the same base length and height. 8 (b) 5 (h) 8 (b) 5 (h) 8 (b) 5 (h) 26 units2 27 units2 50.24 units2 r 2 9 (b) 6 (h) 8 (b 2) 4 (h) 5 (b 1) radius (r) center diameter 4 © Copyright NewPath Learning. All Rights Reserved. 93-4805 www.newpathlearning.com Perimeter & Area
A = 1 2 h (b 1 + b 2) A = A = 1 2 b • h A = A = A Triangle Trapezoid Circle Perimeter Area • Perimeter is . • Area is the number of square units inside the boundary of a two-dimensional figure. • The area of a triangle is one-half of the base length times the height. • The area of a circle is times the square of the radius. • The area of a trapezoid is one-half the height (h) times the sum of the base lengths b 1 and b 2. • To find the perimeter, all side lengths. or substitute 12 for b and 8 for h. P = 9 + 10 + 2 + 7 + 3 + 4 + 2 + 2 + 2 + 5 = 46 units P = 8 + 8 + 12 + 12 = 40 units P = P = 2 b + 2 h y x ( -4 , -2 ) ( -4 , 3 ) ( 4 , 3 ) ( 4 , -2 ) 10 8 12 9 2 2 2 2 4 3 7 5 Rectangle Rectangle base (b) height (h) A = b • h = 8 • 5 = 40 A = b • h Parallelogram • If a triangular section is cut and placed on the opposite side of a parallelogram, it forms a • Therefore, a parallelogram has the same area as a rectangle with the same base length and height. 8 (b) 5 (h) r 2 9 (b) 6 (h) 8 (b 2) 4 (h) 5 (b 1) radius (r) center diameter 4 Key Vocabulary Terms • area • base • circle • height • length • parallelogram • perimeter • rectangle • trapezoid • triangle • width = 8 • 5 = 40 . © Copyright NewPath Learning. All Rights Reserved. 93-4805 www.newpathlearning.com Perimeter & Area \|xiBAHBDy01680pzY
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