WAEC 2022 · Paper 1 · Q19

In the diagram, $|XY| = |YZ|$ and $\angle XYZ = 130^\circ$ . Find the value of $y$ .

Worked solution (try it first)

$|XY| = |YZ|$ , so triangle $XYZ$ is isosceles and its base angles at $X$ and $Z$ are equal.
The angles of the triangle add up to $180^\circ$ : each base angle is $\frac{180^\circ - 130^\circ}{2} = 25^\circ$ , so $\angle YZX = 25^\circ$ .
$WZX$ is a straight line, so $y = 180^\circ - 25^\circ = 155^\circ$ , option D.