WAEC Mathematics 2022 Paper

Concept:Use Pythagoras' theorem to find the missing side lengths, then add all outside edges to get the perimeter.Explanation:In right-angled triangle $\Delta WYZ$, the right angle is at $Z$, so $WY$ is the hypotenuse.By Pythagoras: $WY^2 = WZ^2 + YZ^2$$WY^2 = 3^2 + 4^2 = 9 + 16 = 25$Thus $WY = \sqrt{25} = 5$ cm.In right-angled triangle $\Delta WXY$, the right angle is at $Y$, so $WX$ is the hypotenuse.By Pythagoras: $WX^2 = WY^2 + XY^2$$WX^2 = 5^2 + 12^2 = 25 + 144 = 169$Thus $WX = \sqrt{169} = 13$ cm.Perimeter of quadrilateral $WXYZ = WZ + ZY + YX + XW$$= 3 + 4 + 12 + 13 = 32$ cm.Answer:B. 32 cm