PSLEJKLM is a parallelogram, JLN is an equilateral triangle and LM = MN.
- Find ∠JLM.
- Find ∠LMJ.
- Find ∠NJK.
(a)
LM = MN
Triangle LMN is an isosceles triangle.
∠MLN
= (180° - 142°) ÷ 2
= 38° ÷ 2
= 19° (Isosceles triangle)
∠JLM
= 60° - 19°
= 41° (Equilateral triangle)
(b)
∠JNM
= 60° - 19°
= 41° (Equilateral triangle)
∠JMN
= 180° - 41° - 19°
= 120° (Angles sum of triangle)
∠JML
= 360° - 142° - 120°
= 98° (Angles at a point)
∠KJL
= ∠JLM
= 41° (Alternate angles)
∠KJN
= 60° + 41°
= 101°
Answer(s): (a) 41°; (b) 98°; (c) 101°