The figure is not drawn to scale. CD//FE and ED//GC. Triangles CGD and DEF are isosceles triangles. Find
- ∠e
- ∠f.
(a)
∠DEF = ∠DCG = 78° (ED//GC, DC//EF)
∠CDG
= (180° - 78°) ÷ 2
= 102° ÷ 2
= 51° (Isosceles triangle)
∠EDF
= 180° - 78° - 78°
= 24° (Isosceles triangle)
∠e
= 180° - 78° - 51° - 24°
= 27° (Interior angles, DC//EF)
(b)
∠f
= 180° - 24° - 27°
= 129° (Angles sum of triangle)
Answer(s): (a) 27°; (b) 129°
