JAMB - Mathematics (2005 - No. 19)

Three straight lines EF, GH and LK interest at O as shown above. If ∠KOF = 52^o and ∠LOH = 85^o, calculate the size of ∠EOG.

26^o

43^o

52^o

85^o

∠GOK = 85^o (vertical opposite angle ∠s)
∠EOG + ∠GOK + ∠KOF = 180 (∠s on a straight line)
∠EOg + 85^o + 52^o = 180^o
∠EOG + 137^o = 180^o
∠EOG = 43^o