Khan Academy: Trigonometric Ratios in Right Triangles

Take ratios of sides to a new level. Pupils learn the definitions of the three basic trigonometric ratios in right triangles. Using the definitions, scholars find missing lengths in right triangles, based on a known angle. Individuals...

Calculators ... they are more efficient than tables. Using two 30-60 right triangles, the segment of a playlist on geometry shows that trigonometric ratios for an angle are the same independent of the size of the triangle. The video...

Learn how to find the sine, cosine, and tangent of angles in right triangles.

Sal shows a few examples where he starts with the two legs of a right triangle and he finds the trig ratios of one of the acute angles.

The online assessment demonstrates knowledge of advanced mathematical concepts in Algebra II. The questions test students on trigonometric ratios in right triangles.

Video showing how to derive two basic trigonometric identities.

Find missing angles in isosceles triangles given just one angle. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.

A trigonometric ratio is a ratio between two sides of a right triangle. In this problem, find sin(A) in the given right triangle. Use the ratio of the opposite side over the hypotenuse.

Trigonometry? What's trigonometry. Well, something to do with triangles, right? Right! Right triangles! In this problem, find the missing length of one of the sides. So set this up as a ratio: cosine(A) = adjacent side length divided by...

What are all the parts of a right triangle called? What makes it a right triangle? Legs? Triangles have legs? Hypotenuse? Pythagorean Theorem? The instructor diagrams and identifies all the parts of a right triangle for you.