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

An equilateral triangle has all sides equal, a scalene triangle has no equal sides, and an isosceles triangle has two equal sides.

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

No, a triangle cannot have two right angles because the sum of the angles in a triangle must be 180 degrees. Two right angles would already total 180 degrees, leaving no degrees for the third angle.

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 GradeMath45 min

Learning Objective

I can classify triangles by their sides and angles.

Lesson Flow

Watch Video

9 min

Basics of Triangles and Quadrilaterals

Miacademy & MiaPrep Learning Channel

Guided Notes

9 min

Key concepts students will learn:

•
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.

Practice

14 min

8 questions • Multiple choice & Short answer

Exit Ticket

5 min

“Draw an example of an isosceles triangle. Label which sides are congruent.”

Teacher Guide

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Answer keys for all questions
Differentiation strategies
Extension activities
Printable student handouts

Triangles by Sides and Angles

Learning Objective

Lesson Flow

Watch Video

Guided Notes

Practice

Exit Ticket

Teacher Guide

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