In the figure, GHJK is a parallelogram. JM, MN and GH are straight lines. GKL is an isosceles triangle.
- Find ∠b.
- Find ∠c.
(a)
∠JMG = ∠HGN = 61° (Corresponding angles, GH//MJ)
∠MLG
= 180° - ∠JMG - ∠MGL
= 180° - 61° - 20°
= 99° (Angles sum of triangle)
∠KLG
= 180° - 99°
= 81° (Angles on a straight line)
∠LKG = ∠KLG = 81° (Isosceles triangle)
∠b
= ∠LKG
= 81° (Corresponding angles, HJ//GK)
(b)
∠c
= 180° - 81° - 81°
= 18° (Isosceles triangle GKL)
Answer(s): (a) 81°; (b) 18°