One-third of a straight angle is equal to:

Question

Accepted Answer

The correct option is 3:
To solve this problem, we need to recall the definition of a straight angle. A straight angle is an angle that measures exactly $180^{\circ}$. The question asks for one-third of a straight angle.

Step 1: Identify the measure of a straight angle.
A straight angle measures $180^{\circ}$.

Step 2: Calculate one-third of the straight angle.
To find one-third of $180^{\circ}$, we perform the following calculation:
$ \frac{1}{3} 	imes 180^{\circ} $
$ = \frac{180^{\circ}}{3} $
$ = 60^{\circ} $
Therefore, one-third of a straight angle is $60^{\circ}$.

The incorrect option is 1:
$90^{\circ}$ is the measure of a right angle, not one-third of a straight angle.

The incorrect option is 2:
$180^{\circ}$ is the measure of a straight angle itself, not one-third of it.

The incorrect option is 4:
$20^{\circ}$ is not the correct calculation for one-third of a straight angle.