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