PSLE Hilda has a triangular piece of paper LMN with ML = MN, ∠LMN = 80° and ∠NPP = 65°. 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° - 80°) ÷ 2
= 100° ÷ 2
= 50° (Isosceles triangle)
∠r
= 180° - 65° - 50°
= 65° (Angles sum of triangle)
(b)
∠MLN = ∠MNL = 50°
∠t
= 180° - 65° - 65°
= 50° (Angles on a straight line)
∠s
= 180° - 50° - 50°
= 80° (Angles sum of triangle)
Answer(s): (a) 65°; (b) 80°