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Question
The surface area of a solid cylinder of radius 2.0 cm and height 10.0 cm is equal to ______ (mm)2.
Solution 1
The surface area of a solid cylinder of radius 2.0 cm and height 10.0 cm is equal to 1.5 × 104 (mm)2.
Explanation:
The total surface area of a cylinder of radius r and height h is
S = 2πr (r + h).
Given that,
r = 2 cm = 2 × 1 cm = 2 × 10 mm = 20 mm
h = 10 cm = 10 × 10 mm = 100 mm
∴ S = 2 x 3.14 x 20 x (20+100) = 15072 mm2 = 1.5 × 104 mm2
Solution 2
Surface area = 2πrh + 2πr2 = 2πr (h + r)
= `2 xx 22/7 xx 2 xx 10 (10 xx 10 + 2 xx 10)` mm2
= 1.5 x 104 mm2 Hence, answer is 1.5 x 104.
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