MATHEMATICS · Multi-part · CBSE · Mathematics · Lines and Angles · Lines and Angles
Problem
Lines AB and CD intersect at point O. In clockwise order, name the four angles formed as ∠AOC, ∠COD, ∠DOB, and ∠BOA.
(i) Identify the two pairs of vertically opposite angles at O.
(ii) State the equality relation that holds for each pair of vertically opposite angles and give a brief reason.
(iii) State the relation that holds for the measures of angles that form a linear pair and give a brief reason.
(iv) Using your answers to (ii) and (iii), explain why ∠AOC=∠DOB without measuring any angle.