Question

find the surface area of the cone.
sa = ? π cm²
leave your answer in terms of π
sa = πrl + πr²

Explanation:

Step1: Substitute the values into the formula

Given \(r = 7\) cm and \(l=9\) cm, and the formula \(SA=\pi rl+\pi r^{2}\).
Substitute \(r = 7\) and \(l = 9\) into \(SA=\pi rl+\pi r^{2}\), we get \(SA=\pi\times7\times9+\pi\times7^{2}\).

Step2: Calculate each term

First term: \(\pi\times7\times9 = 63\pi\).
Second term: \(\pi\times7^{2}=\pi\times49 = 49\pi\).

Step3: Add the two terms together

\(SA=63\pi + 49\pi=(63 + 49)\pi\).

Answer:

\(112\pi\)