WAEC 2021 · Paper 1 · Q25

In the diagram, $\triangle XYZ$ has $YZ$ produced to $T$ . If $|XY| = |ZY|$ and $\angle XYT = 40^\circ$ , find $\angle XZT$ .

Worked solution (try it first)

$|XY| = |ZY|$ , so the base angles at $X$ and $Z$ are equal: each is $\frac{180^\circ - 40^\circ}{2} = 70^\circ$ .
Angles on the straight line $YZT$ : $\angle XZT = 180^\circ - 70^\circ$
$= 110^\circ$ , option A.