PSLE Dana has a triangular piece of paper RST with SR = ST, ∠RST = 80° and ∠TUU = 68°. RUT and SUT are straight lines. She folded it along the line UV as shown.
- Find ∠w.
- Find ∠x.
(a)
Length of RS = Length of ST
Triangle RST is an isosceles triangle.
∠STR
= (180° - 80°) ÷ 2
= 100° ÷ 2
= 50° (Isosceles triangle)
∠w
= 180° - 68° - 50°
= 62° (Angles sum of triangle)
(b)
∠SRT = ∠STR = 50°
∠y
= 180° - 68° - 68°
= 44° (Angles on a straight line)
∠x
= 180° - 50° - 44°
= 86° (Angles sum of triangle)
Answer(s): (a) 62°; (b) 86°