An obtuse angle is an angle that measures more than 90 degrees and less than 180 degrees.
It’s unclear why these angles take that name, as the word ‘obtuse’ can be defined as ‘stupid.’ But obtuse could also mean dull and blunt, with the latter defined as ‘not sharp.’ So as obtuse angles aren’t sharp, this could be one reason they’re called such.
It’s important to remember what they’re called and what they look like.
How to Measure an Obtuse Angle
You can measure an obtuse angle using a protractor. It is a handy tool for children to use in maths lessons.
How to Utilize a Protractor to Measure Angles
- Align the angle’s vertex with the cross on the bottom of the protractor.
- Align the line from the vertex with the 0 points on the protractor.
- See where the other line of the angle lines up with the numbers on the protractor.
What is an obtuse triangle?
An obtuse triangle is a triangle where one of the angles is obtuse. It is not a wholly obtuse triangle; a triangle with only obtuse angles would not be a triangle. Only a single angle in a triangle can be obtuse.
Different Types Of Angles
When learning about different angles, obtuse is just one of the terms pupils will learn to use. They’ll also practice identifying other types of angles.
Here’s a summary of these critical terms and visual representations of what these angles look like.
Acute
Acute angles are minor than 90°.
Right (90°)
Right angles are always measured at 90°.
Straight
Straight angles are always 180°.
Reflex
A reflex angle is the ‘outside’ of an angle.
Measured at more than 180° but less than 360°.
Full
A whole angle is always measured at 360°.
