PSLE Jen has a triangular piece of paper RST with SR = ST, ∠RST = 78° and ∠TUU = 66°. 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° - 78°) ÷ 2
= 102° ÷ 2
= 51° (Isosceles triangle)
∠w
= 180° - 66° - 51°
= 63° (Angles sum of triangle)
(b)
∠SRT = ∠STR = 51°
∠y
= 180° - 66° - 66°
= 48° (Angles on a straight line)
∠x
= 180° - 51° - 48°
= 81° (Angles sum of triangle)
Answer(s): (a) 63°; (b) 81°