Lesson: Double-Angle and Half-Angle Identities Mathematics • Second Year of Secondary School

Students will be able to

• derive and recall the double- and half-angle identities for sine, cosine, and tangent from the sum and difference formulas:
• use the identities along with the Pythagorean identities to simplify expressions,
• use the identities to evaluate expressions, including determining the exact values of trigonometric functions, for example, .