Question
In figure, if QT ⊥ PR, ∠TQR = 40° and ∠SPR = 30°, find the value of x and y.

Solution
In ∆QTR,
∠QTR + ∠r + 40° = 180°
| ∠ Angle sum property of a triangle
⇒ 90° + ∠x + 40° = 180°
⇒ ∠r + 130° = 180°
⇒ ∠x = 180° - 130° = 50°
∠x = 50°
In ∠PSR,
y° = x° + 30°
| Exterior angle theorem
= 50° + 30°
= 80°
⇒ y = 80°