PSLE Ivory has a triangular piece of paper GHJ with HG = HJ, ∠GHJ = 80° and ∠JKK = 73°. 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° - 80°) ÷ 2
= 100° ÷ 2
= 50° (Isosceles triangle)
∠m
= 180° - 73° - 50°
= 57° (Angles sum of triangle)
(b)
∠HGJ = ∠HJG = 50°
∠p
= 180° - 73° - 73°
= 34° (Angles on a straight line)
∠n
= 180° - 50° - 34°
= 96° (Angles sum of triangle)
Answer(s): (a) 57°; (b) 96°