5.4 Sum and Difference Identities for Sine and Tangent

Sine of a Sum or Difference

Tangent of a Sum or Difference

Example

Write each function as an expression involving functions of θ.

Finding Function Values and the Quadrant of A + B

Example

Suppose that A and B are angles in standard position, with

Find each of the following:

a) b)

c) the quadrant of A – B

Verifying An Identity using Sum and Difference Identities

Example

Verify that the equation is an identity.