Question

What is the surface area of the cone? Express your answer in terms of π.

Answer 1

The surface area is about 408.47

Explanation:

We must use Pythagorean Theorem in order to find the the height of the cone in order to use the surface area of a cone formula. The formula that you use would be A=πr(r+h2+r2). You already have the radius which is 5.

Pythagorean Theorem

• a^2 + b^2 = c^2

You have two leg measurements of the triangle, one of which is the hypotenuse. The hypotenuse is 21.

• a^2 + (5)^2 = (21)^2
• a^2 +25 = 441

Subtract 25

• a^2 = 416
• a = 20.4

Take the square root of 416 and you get about 20.4. So the height of the cone would be about 20.4.

πr(r+h2+r2) ----> π(5)(5+(20.4)2+(5)2) and you get about 408.47