In each example given below,radius of base of a cylinder and and its height are given. Then find the curved surface area and total surface area.1)r=7 cm,h=10 cm 2)r=1.4 cm ,h=2.1 cm 3)r=2.5 cm ,h=7 cm 4)r=70 cm ,h=1.4 cm 5)r=4.2 cm ,h=14 cm
Answers
Curved surface area of cylinder = CSA = 2πrh
Total surface area of cylinder = TSA = 2πr (h + r) = 2πrh + 2πr² = CSA + 2πr²
1)r=7 cm,h=10 cm
CSA = 2πrh
= 2 × 22/7 × 7 × 10 = 440 cm²
TSA = CSA + 2πr²
= 440 + 2 × 22/7 × 7² = 440 + 308 = 748 cm²
2)r=1.4 cm ,h=2.1 cm
CSA = 2πrh
= 2 × 22/7 × 1.4 × 2.1 = 18.48 cm²
TSA = CSA + 2πr²
= 18.48 + 2 × 22/7 × 1.4² = 18.48 + 12.32 = 30.8 cm²
3)r=2.5 cm ,h=7 cm
CSA = 2πrh
= 2 × 22/7 × 2.5 × 7 = 110 cm²
TSA = CSA + 2πr²
= 110 + 2 × 22/7 × 2.5² = 110 + 39.28 = 149.28 cm²
4)r=70 cm ,h=1.4 cm
CSA = 2πrh
= 2 × 22/7 × 70 × 1.4 = 616 cm²
TSA = CSA + 2πr²
= 616 + 2 × 22/7 × 70² = 616 + 30800 = 31416 cm²
5)r=4.2 cm ,h=14 cm
CSA = 2πrh
= 2 × 22/7 × 4.2 × 14 = 369.6 cm²
TSA = CSA + 2πr²
= 369.6 + 2 × 22/7 × 4.2² = 369.6 + 110.88 = 480.48 cm²