PSLE Elyse has a triangular piece of paper EFG with FE = FG, ∠EFG = 80° and ∠GHH = 69°. EHG and FHG are straight lines. She folded it along the line HJ as shown.
- Find ∠k.
- Find ∠l.
(a)
Length of EF = Length of FG
Triangle EFG is an isosceles triangle.
∠FGE
= (180° - 80°) ÷ 2
= 100° ÷ 2
= 50° (Isosceles triangle)
∠k
= 180° - 69° - 50°
= 61° (Angles sum of triangle)
(b)
∠FEG = ∠FGE = 50°
∠m
= 180° - 69° - 69°
= 42° (Angles on a straight line)
∠l
= 180° - 50° - 42°
= 88° (Angles sum of triangle)
Answer(s): (a) 61°; (b) 88°