PSLE ABCD and BDEF are rhombuses. CGD is a straight line.
- Find ∠DBG.
- Find ∠CDE.
(a)
∠BDC
= (180° - 100°) ÷2
= 80° ÷ 2
= 40° (Isosceles triangle)
∠DBG
= 180° - 122° - 40°
= 18° (Angles sum of triangle)
(b)
∠BFE
= 360° - 280°
= 80° (Angles at a point)
∠BDE = ∠BFE = 80° (Rhombus)
∠CDE
= 80° - 40°
= 40°
Answer(s): (a) 18°; (b) 40°