The figure, not drawn to scale, O is the centre of the circle and DJ // EH // FG. Find
- ∠COF
- ∠CHO
(a)
∠JOE
= 180° - 102°
= 78° (Interior angles, DJ//EO)
∠OFH = ∠OHF = 34° (Isosceles triangle)
∠EOF
= 34° + 34°
= 68° (Exterior angle of a triangle)
∠COF
= 78° + 68°
= 146°
(b)
∠HOF
= 180° - 34° -34°
= 112° (Isosceles triangle)
∠COH
= 360° - 146° - 112°
= 102° (Angles at a point)
CO = OH = Radius
∠CHO
= (180° - 102°) ÷ 2
= 78° ÷ 2
= 39° (Isosceles triangle)
Answer(s): (a) 146°; (b) 39°