WAEC Mathematics 2022 Paper

Concept:The area of a trapezium is half the sum of the parallel sides multiplied by the perpendicular height.Explanation:Let the perpendicular distance be $h$.Area of trapezium $= \frac{(a+b)h}{2}$ where $a$ and $b$ are the parallel sides.Here, $a = 9\text{ cm}$, $b = 12\text{ cm}$, and Area $= 105\text{ cm}^2$.So, $105 = \frac{(9+12)h}{2}$.This gives $105 = \frac{21h}{2}$.Multiplying both sides by $2$: $210 = 21h$.Dividing both sides by $21$: $h = \frac{210}{21} = 10$.Answer:The perpendicular distance between the parallel sides is $10\text{ cm}$.Correct option: C. $10\text{ cm}$.