Question

Find the surface area of a cone with a slant height of 18 inches and a radius of 7 inches

Answer 1

The surface area formula of a cone is:
=Area of base × $\frac{1}{2}$ × perimeter of base × slant height
=$\pi$r² + $\pi$rl
=$\pi$(7)² + $\pi$(7)(18)
=49$\pi$ + 126$\pi$
=175$\pi$ in² (in terms of $\pi$)
=549.7787 in² 
≈ 550 in²

Answer 2

Please see the pic, I'd solved in it.