1. Over Lesson 12–2 A.A B.B C.C D.D 5-Minute Check 1 A cubic inch of water weighs 0.036 pound. A 10- gallon fish tank measures 20 inches by 10 inches by 12 inches. How much will the water in the fish tank weigh if it is filled to capacity?

2. Splash Screen

3. Then/Now You have already found the areas of circles. (Lesson 11–8) Find the volumes of circular cylinders. Find the volumes of composite figures involving circular cylinders.

4. Concept

5. Example 1 A Volume of a Cylinder A. Find the volume of the cylinder. Round to the nearest tenth. Answer: The volume is about 2154.0 cubic feet. V =BhVolume of a cylinder V =πr 2 hReplace B with πr 2. V ≈ 3.14 ● 7 2 ● 14Replace π with 3.14, r with 7, and h with 14. V ≈2154.0Simplify.

6. Example 1 B Volume of a Cylinder B. Find the volume of the cylinder. Round to the nearest tenth. diameter of base 10 m, height 2 m Since the diameter is 10 meters, the radius is 5 meters. Answer: The volume is about 157 cubic meters. V=πr 2 hFormula for volume of a cylinder V≈3.14 ● 5 2 ● 2Replace π with 3.14, r with 5, and h with 2. V≈157Simplify.

7. A.A B.B C.C D.D Example 1 CYP A A.175.9 in 3 B.336 in 3 C.351.7 in 3 D.615.8 in 3 A. Find the volume of the cylinder. Round to the nearest tenth.

8. A.A B.B C.C D.D Example 1 CYP B A.1206.4 cm 3 B.301.4 cm 3 C.226.2 cm 3 D.150.8 cm 3 B. Find the volume of the cylinder with a base diameter of 8 cm and a height of 6 cm. Round to the nearest tenth.

9. Example 2 Height of a Cylinder The volume of the cylinder is 99 cubic inches. Find the height of the cylinder. Round to the nearest tenth. V= BhVolume of a cylinder V= πr 2 h Replace B with πr 2. 99≈ 3.14 ● 3 2 ● hReplace V with 99, π with 3.14, and r with 3.

10. Example 2 Height of a Cylinder Answer: The height is about 3.5 inches. 3.5 ≈ h Divide each side by 28.26. 99 ≈ 28.26hSimplify.

11. A.A B.B C.C D.D Example 2 A.6.0 in. B.6.4 in. C.7.2 in. D.7.5 in. The volume of a cylinder is 678 cubic inches. Find the height of the cylinder. Round to the nearest tenth.

12. End of the Lesson