2. Whiteboardmaths.com © 2004 All rights reserved 5 7 2 1

3. Volume of a Prism Remember: Prisms are 3 dimensional shapes that have a constant cross-sectional area. Triangular-based prism Rectangular-based prism Pentagonal-based prism Hexagonal-based prism Octagonal-based prism Circular-based prism Cylinder

4. Prisms The volume of any prism is simply its: area (base) x height V=A b H 9 m 2 100 cm 2 60 mm 2 2 m 9 cm 3 mm a b c V = 9 x 2 = 18 m 3 V = 100 x 9 = 900 cm 3 V = 60 x 3 = 180 mm 3 Diagrams Not to scale

5. Find the volume of the following prisms. 9 m 2 V = 9 x 5 = 45 m 3 Diagrams Not to scale 8 cm 2 7 mm 2 5 m 4 cm 10 mm 20 mm 2 10 mm 30 m 2 2½ m 40 cm 2 3 ¼ cm V = 8 x 4 = 32 cm 3 V = 7 x 10 = 70 mm 3 V = 20 x 10 = 200 mm 3 V = 30 x 2½ = 75 m 3 V = 40 x 3¼ = 130 cm 3 1 2 3 4 5 6

6. Find the volume of the following prisms. Diagrams Not to scale 4.3 m 2 8.2 cm 2 5.1 m 19.3 cm V = 4.3 x 5.1 = 21.93 m 3 V = 8.2 x 19.3 = 158.26 cm 3 V = 8.2 x 10.1 = 82.82 ft 3 V = 0.7 x 0.4 = 0.28 yd 3 8.2 ft 2 10.1 ft 0.7 yd 2 0.4 yd 1 2 3 4

7. Find the volume of the following prisms. Diagrams Not to scale In each of the following examples the cross-sectional ends have to be calculated. 4 m 2 m V = 4 x 1.5 x 2 = 12 m 3 1.5 m 8 cm 9 cm 4 cm 8 mm 7 mm 6 mm 5 mm 1 2 3 V = ½ (9 x 8) x 4 = 144 cm 3 V = ½ (8 + 6) x 7 x 5 = 245 mm 3 Remember: A = ½ base x height A = ½ the sum of the parallel sides x height

8. h Volume =  r 2 h The Volume of a Cylinder A cylinder is a prism with a circular cross-section. r2r2

9. 10 cm The Volume of a Cylinder Calculate the volume of the following cylinders. 15 m 4.2mm 9.2 mm 3 cm 2 m 1 2 3 V =  r 2 h =  x 3 2 x 10 = 282.7 cm 3 V =  r 2 h =  x 2 2 x 15 = 188.5 m 3 V =  r 2 h =  x 4.6 2 x 4.2 = 279.2 mm 3

10. Volume of a Pyramid Archimedes of Syracuse 287 - 212 BC The volume of a pyramid is 1/3 the volume of the surrounding prism on the same base. In the special case, when the pyramid is a cone, the surrounding prism is a cylinder.

11. Volume of a Pyramid Example Questions: Find the volume of the pyramids shown. 4 cm 7 cm 30 cm 2 7.8 m 2 6 cm 8.3 cm 3.1 m 5 cm 6 cm 7 cm 1 2 3 4 Not to SCALE

12. 45 cm 2 8.3 m 2 9 cm 4.2 m 1 2 4 cm 5 cm 6 cm 4 8 cm 9 cm 6.1 cm 3 Volume of a Pyramid Questions: Find the volume of the pyramids shown. (1 dp) Not to SCALE

13. 6 cm Example Questions: Find the volume of the cones below. (to 1 dp) 1 2 6.2 cm Not to SCALE 15 cm 4.8 cm

14. 12 cm 7.3 cm Example Questions: Calculate the volume of the spheres below. (to 1 dp) 1 2