The figure, not drawn to scale, O is the centre of the circle and EK // FJ // GH. Find
- ∠DOG
- ∠DJO
(a)
∠KOF
= 180° - 102°
= 78° (Interior angles, EK//FO)
∠OGJ = ∠OJG = 34° (Isosceles triangle)
∠FOG
= 34° + 34°
= 68° (Exterior angle of a triangle)
∠DOG
= 78° + 68°
= 146°
(b)
∠JOG
= 180° - 34° -34°
= 112° (Isosceles triangle)
∠DOJ
= 360° - 146° - 112°
= 102° (Angles at a point)
DO = OJ = Radius
∠DJO
= (180° - 102°) ÷ 2
= 78° ÷ 2
= 39° (Isosceles triangle)
Answer(s): (a) 146°; (b) 39°