YZAB is a quadrilateral and OYBA is a trapezium in which OY // BA and ∠ZYB = 108°, ∠YBA = 128°, ∠ZAB = 66° and BA = BY. Find
- ∠YZO
- ∠BYO
- ∠YAB.
(a)
∠YZO
= 360° - 128° -108° - 66°
= 58° (Sum of angles in a quadrilateral)
(b)
∠BYO
= 180° - 128°
= 52° (Interior angles, YO//BC)
(c)
∠YAB
= (180° - 128°) ÷ 2
= 52 ÷ 2
= 26° (Isosceles triangle)
Answer(s): (a) 58°; (b) 52°; (c) 26°