The figure, not drawn to scale, O is the centre of the circle and EK // FJ // GH. Find
- ∠DOG
- ∠DJO
(a)
∠KOF
= 180° - 100°
= 80° (Interior angles, EK//FO)
∠OGJ = ∠OJG = 32° (Isosceles triangle)
∠FOG
= 32° + 32°
= 64° (Exterior angle of a triangle)
∠DOG
= 80° + 64°
= 144°
(b)
∠JOG
= 180° - 32° -32°
= 116° (Isosceles triangle)
∠DOJ
= 360° - 144° - 116°
= 100° (Angles at a point)
DO = OJ = Radius
∠DJO
= (180° - 100°) ÷ 2
= 80° ÷ 2
= 40° (Isosceles triangle)
Answer(s): (a) 144°; (b) 40°