What Is Right Triangle Trigonometry? - Expii

Common Core suggests: "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.".

Section 4.3: Right Triangle Trigonometry

Find Sin, Cos, Tan from Lengths of Triangle Sides - Expii

4.2.1 Right Triangle Trigonometry

Distance Formula - Expii

Right Triangle Trig Extended to Circles with a Model

5.5: Right Triangle Trigonometry - Mathematics LibreTexts

Trigonometry: Solving Right Triangles How? (NancyPi)

4-03 Right Triangle Trigonometry

Find Sin, Cos, Tan from Lengths of Triangle Sides - Expii