Classify triangles by angles, step by step
Name a triangle by its widest corner.
The question
acuterightobtuse
Is this triangle acute, right, or obtuse?
Name this triangle
angles:15°40°125°
angles:15°40°125°
angles:15°40°125°
obtuse
- Every triangle has TWO names — one for its angles and one for its sides — and it has both at once. This question is asking for the ANGLE name, so look only at the angles.
- Classify by the BIGGEST angle — it is the only one that can be a right angle or wider, so it alone decides the type. Here that is 125°.
- More than 90, so it is OBTUSE. One obtuse angle is all it takes — and a triangle can never have two.
How it works.
- 01
Every triangle has TWO names — one for its angles and one for its sides — and it has both at once. This question is asking for the ANGLE name, so look only at the angles.
- 02
Classify by the BIGGEST angle — it is the only one that can be a right angle or wider, so it alone decides the type. Here that is 125°.
- 03
More than 90, so it is OBTUSE. One obtuse angle is all it takes — and a triangle can never have two.