These are the resources that support this Virginia Standard.
T.IE.2.a - Use trigonometric identities to make algebraic substitutions to simplify and verify trigonometric identities. The basic trigonometric identities include i) reciprocal identities; ii) Pythagorean identities; iii) sum and difference identities; iv) double-angle identities; and v) half-angle identities.
In this TI Nspire tutorial for the TI-Nspire CAS, the Calculator window is used to find the trigonometric identities for addition and subtraction of sine and cosine.