Question

In the given figure, if $\angle AOC={65}^{\circ }$, then $\angle COB=$ ___.

• A. ${65}^{\circ }$
• B. ${115}^{\circ }$
• C. ${105}^{\circ }$
• D. ${80}^{\circ }$

Answer 1

The correct option is B

${115}^{\circ }$

$\Rightarrow \angle AOC+\angle COB={180}^{\circ }\text{[Angles on a straight line add to}{180}^{\circ }]$

$\Rightarrow {65}^{\circ }+\angle COB={180}^{\circ }$

$\Rightarrow \angle COB=180-{65}^{\circ }={115}^{\circ }$