PSLEGHJK is a parallelogram, GJL is an equilateral triangle and JK = KL.
- Find ∠GJK.
- Find ∠JKG.
- Find ∠LGH.
(a)
JK = KL
Triangle JKL is an isosceles triangle.
∠KJL
= (180° - 142°) ÷ 2
= 38° ÷ 2
= 19° (Isosceles triangle)
∠GJK
= 60° - 19°
= 41° (Equilateral triangle)
(b)
∠GLK
= 60° - 19°
= 41° (Equilateral triangle)
∠GKL
= 180° - 41° - 19°
= 120° (Angles sum of triangle)
∠GKJ
= 360° - 142° - 120°
= 98° (Angles at a point)
∠HGJ
= ∠GJK
= 41° (Alternate angles)
∠HGL
= 60° + 41°
= 101°
Answer(s): (a) 41°; (b) 98°; (c) 101°