In the figure, WXYZ is a parallelogram. YB, BC and WX are straight lines. WZA is an isosceles triangle.
- Find ∠b.
- Find ∠c.
(a)
∠YBW = ∠XWC = 60° (Corresponding angles, WX//BY)
∠BAW
= 180° - ∠YBW - ∠BWA
= 180° - 60° - 21°
= 99° (Angles sum of triangle)
∠ZAW
= 180° - 99°
= 81° (Angles on a straight line)
∠AZW = ∠ZAW = 81° (Isosceles triangle)
∠b
= ∠AZW
= 81° (Corresponding angles, XY//WZ)
(b)
∠c
= 180° - 81° - 81°
= 18° (Isosceles triangle WZA)
Answer(s): (a) 81°; (b) 18°