# Precalculus

posted by
**Melinda**
.

1. What two common identities are most useful for simplifying 2tanx/(sin^2x + cos^2x - tan^2x)?

Two identities are: sin^2x + cos^2x = 1 and tan2x=2tanx/1-tan^2x

posted by
**Melinda**
.

1. What two common identities are most useful for simplifying 2tanx/(sin^2x + cos^2x - tan^2x)?

Two identities are: sin^2x + cos^2x = 1 and tan2x=2tanx/1-tan^2x