The figure is not drawn to scale. BC//ED and DC//FB. Triangles BFC and CDE are isosceles triangles. Find
- ∠j
- ∠k.
(a)
∠CDE = ∠CBF = 72° (DC//FB, CB//DE)
∠BCF
= (180° - 72°) ÷ 2
= 108° ÷ 2
= 54° (Isosceles triangle)
∠DCE
= 180° - 72° - 72°
= 36° (Isosceles triangle)
∠j
= 180° - 72° - 54° - 36°
= 18° (Interior angles, CB//DE)
(b)
∠k
= 180° - 27° - 18°
= 135° (Angles sum of triangle)
Answer(s): (a) 18°; (b) 135°
