PSLE Wendy has a triangular piece of paper LMN with ML = MN, ∠LMN = 76° and ∠NPP = 72°. LPN and MPN are straight lines. She folded it along the line PQ as shown.
- Find ∠r.
- Find ∠s.
(a)
Length of LM = Length of MN
Triangle LMN is an isosceles triangle.
∠MNL
= (180° - 76°) ÷ 2
= 104° ÷ 2
= 52° (Isosceles triangle)
∠r
= 180° - 72° - 52°
= 56° (Angles sum of triangle)
(b)
∠MLN = ∠MNL = 52°
∠t
= 180° - 72° - 72°
= 36° (Angles on a straight line)
∠s
= 180° - 52° - 36°
= 92° (Angles sum of triangle)
Answer(s): (a) 56°; (b) 92°