Finding Missing Sides with Pythagoras

8th GradeMath50 min

Learning Objective

I can use the Pythagorean theorem to find missing side lengths of right triangles, relating them to the angles.

Lesson Flow

Watch Video

7 min

How Special Right Triangles Work | 45-45-90 and 30-60-90

Does Math for Coffee

Guided Notes

10 min

Key concepts students will learn:

  • In a 45-45-90 triangle, the two sides opposite the 45 degree angles are congruent, and the hypotenuse is equal to the side length times the square root of 2.

  • In a 30-60-90 triangle, the shortest side is opposite the 30 degree angle, and the hypotenuse is twice the length of the shortest side.

  • In a 30-60-90 triangle, the longer leg is equal to the short side times the square root of 3.

Practice

15 min

12 questions • Multiple choice & Short answer

Exit Ticket

5 min

In a 45-45-90 triangle, one of the legs has a length of 7. What is the length of the hypotenuse? Show your work.

Teacher Guide

Get the complete package:

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