PSLE Fiona has a triangular piece of paper FGH with GF = GH, ∠FGH = 84° 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° - 84°) ÷ 2
= 96° ÷ 2
= 48° (Isosceles triangle)
∠l
= 180° - 74° - 48°
= 58° (Angles sum of triangle)
(b)
∠GFH = ∠GHF = 48°
∠n
= 180° - 74° - 74°
= 32° (Angles on a straight line)
∠m
= 180° - 48° - 32°
= 100° (Angles sum of triangle)
Answer(s): (a) 58°; (b) 100°