PSLE Gabby has a triangular piece of paper FGH with GF = GH, ∠FGH = 80° and ∠HJJ = 66°. 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° - 80°) ÷ 2
= 100° ÷ 2
= 50° (Isosceles triangle)
∠l
= 180° - 66° - 50°
= 64° (Angles sum of triangle)
(b)
∠GFH = ∠GHF = 50°
∠n
= 180° - 66° - 66°
= 48° (Angles on a straight line)
∠m
= 180° - 50° - 48°
= 82° (Angles sum of triangle)
Answer(s): (a) 64°; (b) 82°