WAEC Mathematics 2025 Paper

Concept:The total surface area of a solid circular cone is the sum of its curved surface area and the area of its circular base.Explanation:For a cone with base radius $r$ and slant height $l$, the total surface area is:$$\text{TSA} = \pi r l + \pi r^2$$This can be simplified by factoring out $\pi r$:$$\text{TSA} = \pi r (l + r)$$From the question, the base radius is $r = 3\text{ cm}$ and the slant height is $l = 4\text{ cm}$.Take $\pi = \frac{22}{7}$ and substitute the given values:$$\text{TSA} = \frac{22}{7} \times 3 (4 + 3)$$First, add the values inside the bracket:$$\text{TSA} = \frac{22}{7} \times 3 \times 7$$The factor $7$ cancels with the denominator $7$:$$\text{TSA} = 22 \times 3 = 66$$Hence, the total surface area of the cone is $66\text{ cm}^2$.Answer:The correct option is A, $66\text{ cm}^2$.