Precalculus : Sum and Difference Identities For Tangent

Example Questions

Example Question #1 : Sum And Difference Identities

In the problem below, and .

Find .      Explanation:

Since and is in quadrant I, we can say that and and therefore: So .

Since and is in quadrant I, we can say that and and therefore: .

So Using the tangent sum formula, we see: Example Question #2 : Sum And Difference Identities

In the problem below, and .

Find .      Explanation:

Since and is in quadrant I, we can say that and and therefore: So .

Since and is in quadrant I, we can say that and and therefore: So .

Using the tangent sum formula, we see: Example Question #1 : Sum And Difference Identities

Given that and , find .      Explanation:

Jump straight to the tangent sum formula: From here plug in the given values and simplify. Example Question #1 : Sum And Difference Identities

Which of the following expressions best represents ?      Explanation:

Write the identity for . Set the value of the angle equal to .  Substitute the value of into the identity. All Precalculus Resources 