Read a protractor scale, estimate turns and name acute, obtuse and reflex angles.
Example 1
Which estimate in degrees is closest to the smaller angle shown at O?
Angle at OShow worked answer
Answer: 120∘
- Compare the drawn angle with benchmarks of 90∘ and 180∘.
- Of the offered estimates, 120∘ is closest.
Example 2
Equal wedges of 90∘ are drawn around one point with no gaps or overlaps. How many wedges fit in one full turn?
Show worked answer
Answer: 4
- A full turn is 360∘.
- 90360=4 wedges. A protractor can mark each 90∘ turn.
Example 3
Measure the marked angle at O using the protractor scale. Give degrees.
Protractor: zero on the rightShow worked answer
Answer: 30
- Start at 0∘ on the right-hand ray.
- Read anticlockwise to where the highlighted ray meets the scale: 30∘.