Question

If AOB is a straight line and $\angle BOC={120}^{\circ }$, then $\angle x=$_________.

• A. ${180}^{\circ }$
• B. ${180}^{\circ }$
• C. ${60}^{\circ }$
• D. ${270}^{\circ }$

Answer 1

The correct option is C ${60}^{\circ }$

Given: AOB is a straight line.
A Linear pair is a pair of adjacent angles where the non-common sides form a straight line.
Here, $\angle AOC$ and $\angle BOC$ form a linear pair.
We know that sum of angles of a linear pair = ${180}^{\circ }$.
Hence, $\angle AOC$+ $\angle BOC$= ${180}^{\circ }$
$\Rightarrow$$\angle x+{120}^{\circ }$= ${180}^{\circ }$
$\Rightarrow$$\angle x={180}^{\circ }-{120}^{\circ }$
$\Rightarrow$$\angle x={60}^{\circ }$