PSLE In the figure, CDEF is a parallelogram. AFC and BFE are straight lines and AB = BC. ∠ABF = 31° and ∠DEF = 60°.
- Find ∠EFC.
- Find ∠FBC.
(a)
∠EFC
= 180° - 60°
= 120° (Interior angles)
(b)
∠AFB
= ∠EFC
= 120° (Vertically opposite angles)
∠BAF
= 180° - 120° - 31°
= 29° (Angles sum of triangle)
∠BCF = ∠BAF (Isosceles triangle)
∠ABC
= 180° - 29° - 29°
= 122° (Angles sum of triangle)
∠FBC
= 122° - 31°
= 91°
Answer(s): (a) 120°; (b) 91°