Geometry

1. Geometry Surface Area of Cylinders

2. Surface Area • Cylinder – (circular prism) a prism with two parallel, equal circles on opposite sides. To find the surface area of a cylinder we can add up the areas of the separate faces.

3. Surface Area • In a cylinder there are a pair of opposite and equal circles. We can find the surface area of a cylinder by adding the areas of the two blue ends (A) and the yellow sides (B). A B

4. Surface Area • We can find the area of the two ends (A) by using the formula for the area of a circle. • A = π r2 5cm A 8cm B

5. Surface Area • We can find the area of the two ends (A) by using the formula for the area of a circle. • A = π r2 5cm A 8cm B

6. Surface Area • If we “unwrapped” the cylinder, what shape would the outside “B” be? 5cm A 8cm B

7. Surface Area • “B” would be in the shape of a rectangle, with the height forming one side and the circumference of the top forming the second side. 5cm A 8cm B

8. Surface Area • A = b * h • A =2πr * h 5cm A 8cm B

9. Surface Area • A =2πr * h • A = 2 (3.14) (5) * 8 5cm A 8cm B

10. Surface Area • A =2πr * h • A = 251.2 cm2 5cm A 8cm B

11. Surface Area • A =2πr * h • A = 251.2 cm2 5cm A 8cm B

12. Surface Area • Sketch cylinder and copy table. Work together to find the S.A.

13. Surface Area • Sketch cylinder and copy table. Calculate S.A. • Assignment 4.1m A A 1.9m