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5.3 – Circumference & Area of Circles. Circumference. Circumference The distance around a circle C = 2 π r This is a one-dimensional measurement!. Circumference. Area. Area of a circle The number of square units that fit inside a circle A = π r 2 This is a two-dimensional
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Circumference • Circumference • The distance around a circle • C = 2πr This is a one-dimensional measurement!
Area • Area of a circle • The number of square units that fit inside a circle • A = πr2 This is a two-dimensional measurement!
Be able to work backwards! • What is the radius of a circle whose circumference is 25.1 cm (round to the nearest hundredth)
What is the diameter of a circle whose circumference is 84 yds (round to the nearest hundredth)
Apply • What is the area of a circle whose radius is 4.23 meters?
Be able to work backwards! • What is the radius of a circle whose area is 98.7 square feet? (round to the nearest hundredth)
What is the diameter of a circle whose area is 579.568 square inches? (round to the nearest hundredth)
Shaded Area • If part is shaded and part is unshaded … • Find the area of the BIG and subtract the area of the SMALL • If it is all shaded or all unshaded … • Find the area of the pieces and add it all together.