CLASS NOTES: How to Measure Angles
What you’ll need: a Protractor, a Pencil, and
your knowledge of how to classify/name an H
Instructions: Measure FGH
Hole & Vertex
Steps What to do HINTS
Step Put your pencil through
the hole of the
Using your pencil, make the rays longer so they extend beyond your
Step Put your pencil on the
Make sure the numbers on your protractor are facing you correctly.
The vertex of this angle is Point G
Step Line-up the protractor. This may mean your protractor is crooked like it is above.
Step Record both values
where the 2nd ray
Count by 10s until you reach the second ray.
4 crosses the protractor.
Step DOUBLE CHECK YOUR
WORK… Ask yourself,
If the answer is YES, your measurements are correct!!! (120 + 60=180)
5 “Do both numbers add
up to 180o?”
Step Name the angle. That’s
the number you
Is the angle: 1-right, 2-acute, 3-obtuse, 4-straight angle or 5-zero
6 choose. This angle is obtuse, and the definition of an obtuse angle. is “An
angle whose measure is greater than 90 and less than 180”. Which
number is between 90 and 180? 120 is, so this angle is 120o. Circle