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Learn how to find the circumference and area of circles, as well as solve problems involving diameter and radius. Also, explore calculations for compound shapes.
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Chapter 26 Circles & Other Shapes
Circumference • Remember circumference = distance around the outside of a circle • C = π× d • OR • C = 2 × π× r
Examples • A circle has a diameter of 18cm. What is its circumference • A dinner plate has a radius of 14cm. What is its circumference? • The circumference of a bike wheel is 190cm. What is its diameter?
Area A = π× r2 Examples • A rug has a radius of 60cm. What is its area? • A plate has a diameter of 30cm. What is its area? • A circle has an area of 6.7cm2. What is its radius and diameter?
Harder Examples Examples • The top of a can has a diameter of 8.4cm. What is its a) perimeter b) area?
2) Find the circumference & area of a semi-circle which has a diameter of 15cm 3) Find the area of the following shape if its radius is 5.3cm
4) A circle has an area of 162cm2. What is its circumference? 5) A circle has a circumference of 14π cm. What is its area?
Compound Shapes Examples Find the areas of the shapes below