A solid cone has a lateral surface area of 100p square centimeters and a total surface area of 269p square centimeters. Find the base radius of the cone.

Question

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Answer 1

total surface area - lateral surface area = area of base

269π - 100π = 169π

 

Area of base = πr²

169π = πr²                      divide both sides by π

169 = r²                          take square root of both sides

±13 = r                           only the positive value makes sense here.

 

The radius of the base is 13.