A straight angle, also known as a 180-degree angle, is defined as an angle that measures exactly 180°. It forms a straight line whose arms lie in opposite directions from the vertex. It is thus also called ‘flat angle’ and is represented using the symbol π (pie).

A few more examples of straight angle are shown below:

Straight Angles in Real Life

Hands of a clock showing 6’ o clock

Corner of an inclined plane of a staircase

The angle in a see-saw

Facts to Remember

A straight angle:

Can be formed by rotating one arm of an angle by 180° with respect to the other

Can be formed by joining two right angles

Measures exactly half of a revolution

Which of the following options given in the clock timing forms a straight angle?

Solution:

As we know, Straight angles are angles that measure 180° Hence, option (d) is a straight angle