 Page Two Example 5: A spherical cup has diameter 15 cm. How much liquid will it hold? 
V = 4·π·r3 ÷ 2 (half a sphere)3 V = 4·π·(7.5)3 ÷ 2 (radius is half the diameter) 3 V = 883.6 cm3 which will hold 883.6 ml Example 6: A spherical top on a silo needs to be painted. Its diameter is 10 m. One can of paint covers 50 m2 and costs $35. What will it cost to paint the cap with two coats? 
Step 1: Find the area of a half sphere with radius 5 m:SA = 4·π·(5)2 ÷ 2 SA = 157.08 m2 Step 2: Double it because two coats are needed SA = 314.16 m2 Step 3: Find the number of cans needed: No. of cans = 314.16 ÷ 50 = 6.28 or 7 cans Step 4: Find the cost: Cost = 7 x $35 = $245 |