PSLE In the figure, BCE and GFE are straight lines and FC is parallel to ED. ∠FGB is a right angle, ∠GBC = 49°, ∠BCD = 111° and ∠EFC = 68°.
- Find ∠BCF.
- Find ∠CDE.
(a)
∠BEG
= 180° - 90° - 49°
= 41° (Angles sum of triangle)
∠ECF
= 180° - 68° - 41°
= 71° (Angles sum of triangle)
∠BCF
= 180° - 71°
= 111° (Angles on a straight line)
(b)
∠ECD
= 360° - 111° - 71° - 111°
= 67° (Angles at a point)
∠CDE
= 180° - 67° - 67°
= 46°
Answer(s): (a) 111°; (b) 46°