The figure is not drawn to scale. ZBCD is a trapezium and ZB // DC. Given that ZD = ZA, ∠DZA = 73° and ∠ZBC = 100°.
- Find ∠BCD
- Find ∠ZAD
- Find ∠ADC
(a)
∠BCD
= 180° - 100°
= 80° (Interior angles, ZB//DC)
(b)
∠ZAD
= (180° - 73°) ÷ 2
= 107° ÷ 2
= 53.5° (Isosceles triangle)
(c)
∠ADC
= ∠ZAD
= 53.5° (Alternate angles, ZB//DC)
Answer(s): (a) 80°; (b) 53.5°; (c) 53.5°