Solving Right Triangles with Trig Ratios

9th GradeMath40 min

Learning Objective

I can solve the unknown side of right angles triangles using trigonometric ratios

Lesson Flow

Watch Video

11 min

Solve Right Triangles 1

YourMathGal

Guided Notes

8 min

Key concepts students will learn:

  • Solving a right triangle means stating the measures of the three angles and the lengths of the three sides.

  • If angle A is 40° and angle C is 90°, then angle B must be 50 degrees because angles A and B must add up to 90°.

  • To solve for an unknown side, you can set up an equation using sine, cosine, or tangent, but you must know at least one side of the right triangle.

Practice

12 min

5 questions • Multiple choice & Short answer

Exit Ticket

5 min

In a right triangle, angle A is 35° and the side opposite to it (side a) is 15 units long. Find the length of the hypotenuse (side c). Round your answer to the nearest tenth.

Teacher Guide

Get the complete package:

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