WAEC 2025 · Paper 1 · Q24✱✱

Solid mensuration

Find the total surface area of a solid circular cone with base radius $3\text{ cm}$ and slant height $4\text{ cm}$ . $\left[\pi = \frac{22}{7}\right]$

Worked solution (try it first)

A solid cone has a curved surface $\pi rl$ and a base $\pi r^2$ : a total of $\pi r(r + l)$ .
$\frac{22}{7} \times 3 \times (3 + 4) = 22 \times 3$
$= 66\text{ cm}^2$ , option A.

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