The angles in a triangle measure 45° and 45°. What is the measure of the third angle, and what type of triangle is it based on its angles?

The third angle is 90°, making it a right triangle.

Triangles by Sides and Angles

5th Grade•45 minutes

I can classify triangles by their sides and angles.

A triangle is a shape that has three sides and three angles.

Triangles can be classified by their angles (right, acute, obtuse) or by their sides (equilateral, scalene, isosceles).

The interior angles of a quadrilateral always add up to 360 degrees, while the interior angles of a triangle always add up to 180 degrees.

This lesson includes 8 practice questions to reinforce learning.

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1. A triangle has angles measuring 30°, 60°, and 90°. What type of triangle is it based on its angles?

2. Explain the difference between an equilateral, scalene, and isosceles triangle in terms of their side lengths.

3. Can a triangle have two right angles? Explain your answer.

...and 5 more questions

Basics of Triangles and Quadrilaterals

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