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° - 144°) ÷ 2
= 36° ÷ 2
= 18° (Isosceles triangle)
∠JLM
= 60° - 18°
= 42° (Equilateral triangle)
(b)
∠JNM
= 60° - 18°
= 42° (Equilateral triangle)
∠JMN
= 180° - 42° - 18°
= 120° (Angles sum of triangle)
∠JML
= 360° - 144° - 120°
= 96° (Angles at a point)
∠KJL
= ∠JLM
= 42° (Alternate angles)
∠KJN
= 60° + 42°
= 102°
Answer(s): (a) 42°; (b) 96°; (c) 102°