PSLE Joelle has a triangular piece of paper GHJ with HG = HJ, ∠GHJ = 76° and ∠JKK = 65°. GKJ and HKJ are straight lines. She folded it along the line KL as shown.
- Find ∠m.
- Find ∠n.
(a)
Length of GH = Length of HJ
Triangle GHJ is an isosceles triangle.
∠HJG
= (180° - 76°) ÷ 2
= 104° ÷ 2
= 52° (Isosceles triangle)
∠m
= 180° - 65° - 52°
= 63° (Angles sum of triangle)
(b)
∠HGJ = ∠HJG = 52°
∠p
= 180° - 65° - 65°
= 50° (Angles on a straight line)
∠n
= 180° - 52° - 50°
= 78° (Angles sum of triangle)
Answer(s): (a) 63°; (b) 78°