Trigonometry with right triangles

Learn the basics of trigonometry: What are sine, cosine, and tangent? How can we use them to solve for unknown sides and angles in right triangles?

Learn about the relationship between the sine of an angle and the cosine of its complementary angle, which is the angle that completes to 90°.

Learn to find the sine, cosine, and tangent of 45-45-90 triangles and also 30-60-90 triangles.

Learn about a very special trigonometric identity that follows from the Pythagorean theorem.