The figure, not drawn to scale, O is the centre of the circle and DJ // EH // FG. Find
- ∠COF
- ∠CHO
(a)
∠JOE
= 180° - 96°
= 84° (Interior angles, DJ//EO)
∠OFH = ∠OHF = 30° (Isosceles triangle)
∠EOF
= 30° + 30°
= 60° (Exterior angle of a triangle)
∠COF
= 84° + 60°
= 144°
(b)
∠HOF
= 180° - 30° -30°
= 120° (Isosceles triangle)
∠COH
= 360° - 144° - 120°
= 96° (Angles at a point)
CO = OH = Radius
∠CHO
= (180° - 96°) ÷ 2
= 84° ÷ 2
= 42° (Isosceles triangle)
Answer(s): (a) 144°; (b) 42°