slant height of a solid right circular come is 7cm and total surface area 147.84 cm .find the radius of the base of the cone
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Answered by
25
Let the radius be r
Formula:
Total Surface of a right circular cone = πrl + πr²
Find the radius:
Given that the slanted height is 7 cm and the surface area is 147.84 cm²
147.84 = πr(7) + πr²
147.84 = πr(7r + r²)
7r + r² = 1176/25
r² + 7r - 1176/25 = 0
25r² + 175r - 1176 = 0
(5r - 21) (5r + 56) = 0
r = 21/5 or r = - 56/5 (rejected, length cannot negative)
r = 21/5 = 4.2 cm
Answer: The radius is 4.2 cm
Answered by
0
Answer:
The answer will be 4.2cm
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