PSLE ABCD is a rhombus. DFB and DECG are straight lines.
- Find ∠ABD.
- Find ∠DCG.
- Find ∠DFE.
(a)
∠ABD
= (180° - 100°) ÷ 2
= 40° (Isosceles triangle)
(b)
∠BCD
= ∠BAD
= 100° (Rhombus)
∠DCG
= 180° - 100°
= 80° (Angles on a straight line)
(c)
∠EBF
= ∠ABF
= 40° (Rhombus)
∠BEF
= 180° - 63°
= 117° (Angles on a straight line)
∠DFE
= 40° + 117°
= 157° (Exterior angle of a triangle)
Answer(s): (a) 40° (b) 80° (c) 157°