Classify a triangle with angles 25, 35, 120

Step by step

The question

Question: find what kind of triangle has angles 25°, 35°, 120°.

1 Find the biggest angle

The biggest angle is 120°.

Only the biggest angle decides the name.

120 is more than 90.

Careful!

Every triangle has at least two acute angles.

So they do not decide.

Only the biggest angle does.

2 Name it

So the triangle is obtuse.

3 Check

Let's check: the angles must add up to 180°.

They do.

So it is a real triangle, and it is obtuse.

Let's look back.

First: find the biggest angle.

Then: name it.

Last: check.