Question

In the given figure, if $\angle CAD={150}^{\circ }$ and $\angle ABC={60}^{\circ },$ then reflex $\angle ACB=$___ .

• A. 1 right angle
• B. 2 right angles
• C. 3 right angles
• D. 4 right angles

Answer 1

The correct option is C

3 right angles

$\angle ACB+\angle ABC=\angle DAC$
[Exterior angle property]
$\angle ACB+{60}^{\circ }={150}^{\circ }\angle ACB={90}^{\circ }\therefore \text{Reflex}\angle ACB={360}^{\circ }-{90}^{\circ }={270}^{\circ }=3\times {90}^{\circ }=3\text{right angles}$