Being able to identify an angle can help us in this lesson. Let's try this problem to review.
Select the obtuse angle:
Use this image to help you:
Rotate each angle so that one arm lies over the start.
The answer is Option C.
A full revolution is made up of 360 degrees, a single degree is written 1\degree.
Let's learn more about angles on a straight line.
Find the size of the missing angle.
Subtract the given angle from 180\degree.
The two angles should add up to 180\degree since they lie on a straight line. So to find the missing angle we can subtract 129\degree from 180\degree .
Angles on a straight line always add up to 180 degrees.
Investigate with and without digital technologies, angles on a straight line, angles at a point and vertically opposite angles. Use results to find unknown angles.