PSLE Yoko has a triangular piece of paper FGH with GF = GH, ∠FGH = 76° and ∠HJJ = 74°. FJH and GJH are straight lines. She folded it along the line JK as shown.
- Find ∠l.
- Find ∠m.
(a)
Length of FG = Length of GH
Triangle FGH is an isosceles triangle.
∠GHF
= (180° - 76°) ÷ 2
= 104° ÷ 2
= 52° (Isosceles triangle)
∠l
= 180° - 74° - 52°
= 54° (Angles sum of triangle)
(b)
∠GFH = ∠GHF = 52°
∠n
= 180° - 74° - 74°
= 32° (Angles on a straight line)
∠m
= 180° - 52° - 32°
= 96° (Angles sum of triangle)
Answer(s): (a) 54°; (b) 96°