Question

Describing a Triangle
 

A triangle has angle measures 40 degrees, 40 degrees, and 100 degrees.

Which statements are true about the triangle? Select all that apply.
The triangle is acute.
The triangle is obtuse.
It is an isosceles triangle.
It is a scalene triangle.
It is an equilateral triangle.
The angles add up to 180°.

Answer 1

True:
- The triangle is obtuse. (One angle is 100°, which is > 90°.)
- It is an isosceles triangle. (Two angles are 40° and 40°, so two sides are equal.)
- The angles add up to 180°. (40° + 40° + 100° = 180°.)

False:
- The triangle is acute. (Not all angles < 90°.)
- It is a scalene triangle. (Not all sides/angles are different.)
- It is an equilateral triangle. (Equilateral requires all angles 60°.)