Basic Trigonometric Identities: Pythagorean Identities and Cofunction Identities

The video tutorial covers trigonometric identities, starting with an introduction to the six trigonometric functions: sine, cosine, tangent, cosecant, secant, and cotangent. It explains the reciprocal relationships among these functions and delves into specific identities, such as tangent being sine over cosine and cotangent being cosine over sine. The Pythagorean identities are derived using the Pythagorean theorem, leading to expressions like sine squared plus cosine squared equals one. The tutorial also explores cofunction identities, showing how sine and cosine relate to complementary angles using the unit circle.

Describe the cofunction identities mentioned in the text.

How can we express sine of theta in terms of cosine?