WAEC Mathematics 2020 Paper

Concept:The angle subtended by a chord at the centre of a circle is twice the angle subtended by it at any point on the remaining part of the circumference.Explanation:In $\triangle NLM$, the sum of interior angles is $180^\circ$.So, $\angle LNM = 180^\circ - (\angle NLM + \angle LMN)$.Thus, $\angle LNM = 180^\circ - (74^\circ + 39^\circ)$.This gives $\angle LNM = 180^\circ - 113^\circ = 67^\circ$.Both $\angle LNM$ and $\angle LOM$ are subtended by chord $LM$.Since $\angle LOM$ is at the centre and $\angle LNM$ is at the circumference,$\angle LOM = 2 \times \angle LNM$.Therefore, $x = 2 \times 67^\circ = 134^\circ$.Answer:$x = 134^\circ$Option A is the correct answer.