PSLE Yoko has a triangular piece of paper RST with SR = ST, ∠RST = 76° and ∠TUU = 75°. 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° - 76°) ÷ 2
= 104° ÷ 2
= 52° (Isosceles triangle)
∠w
= 180° - 75° - 52°
= 53° (Angles sum of triangle)
(b)
∠SRT = ∠STR = 52°
∠y
= 180° - 75° - 75°
= 30° (Angles on a straight line)
∠x
= 180° - 52° - 30°
= 98° (Angles sum of triangle)
Answer(s): (a) 53°; (b) 98°