The figure is not drawn to scale. RS//UT and TS//VR. Triangles RVS and STU are isosceles triangles. Find
- ∠b
- ∠c.
(a)
∠STU = ∠SRV = 72° (TS//VR, SR//TU)
∠RSV
= (180° - 72°) ÷ 2
= 108° ÷ 2
= 54° (Isosceles triangle)
∠TSU
= 180° - 72° - 72°
= 36° (Isosceles triangle)
∠b
= 180° - 72° - 54° - 36°
= 18° (Interior angles, SR//TU)
(b)
∠c
= 180° - 25° - 18°
= 137° (Angles sum of triangle)
Answer(s): (a) 18°; (b) 137°