# Similarity and Trig Ratios

Videos and lessons to help High School students learn how to understand that by similarity, side ratios in right triangles are properties of the angles in the triangle, leading to definitions of trigonometric ratios for acute angles.

Common Core: HSG-SRT.C.6

Intro to Trig Ratios
Preliminary connections between similar triangles and trigonometry.

Trig and similar triangles.

Labeling Sides
Learn how to label the sides of a right triangle as 'hypotenuse', 'opposite', and 'adjacent' in relation to one of the triangle's acute angles.

Writing Trig Ratios
Writing the basic trig ratios given three side lengths; or given two side lengths.

Writing Ratios part 1
Learn how to write the three primary trig. ratios for a right triangle given the three side lengths.

Writing Ratios part 2
Learn how to write the three primary trig. ratios for a right triangle given two of the three side lengths.

Finding a Side Using Trig
Using the tangent function to find an unknown side in a right triangle - two examples... one where the missing side ends up on the top of the ratio in the trig equation, and another where it ends up on the bottom.

Finding an Angle Using Trig
Using the inverse tangent function to find an angle in a right.

Trig Ratios on a Calculator
Introduction to the trig function buttons (SIN,COS,TAN), and inverse function buttons (INVERSE SIN,COS,TAN) on a calculator.

Introduction to Trigonometry
Lesson Objective
Calculate sine, cosine and tangent

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