Topic explanation

Standard explanation

Apply sin2x, cos2x, or tan2x identities, then account for the changed angle and period.

Key points

• Double-angle equations
• rule
• worked example
• Double-angle equations: Apply sin2x, cos2x, or tan2x identities, then account for the changed angle and period.
• CONCEPT AND RULE: Apply sin2x, cos2x, or tan2x identities, then account for the changed angle and period.
• METHOD: For double-angle equations, identify the given information and required result. Select the matching
• Apply sin2x, cos2x, or tan2x identities, then account for the changed angle and period.
• Worked pattern: sin2x=0 gives 2x=npi, so x=npi/2.

Labelled diagram