In the figure, ZAD and CAB are right-angled triangles. DA is parallel to CB. Find
- ∠ABC
- ∠ADC
(a)
∠CAD
= 360° - 90° - 90° - 120°
= 60° (Angles at a point)
∠ACB = ∠CAD = 60° (Alternate angles)
∠ABC
= 180° - ∠CAB - ∠ACB
= 180° - 90° - 60°
= 30° (Angles sum of triangle)
(b)
∠ADC
= 180° - ∠CAD - ∠ACD
= 180° - 60° - 87°
= 33° (Angles sum of triangle)
Answer(s): (a) 30°; (b) 33°