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Trigonometric Identities

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Trigonometric Identities - Exercises | IB Math AAHL | Perplex

Trigonometric Identities

Trigonometric Identities

Applications of trigonometric identities such as sin2θ+cos2θ=1, sin2θ=2sinθcosθ and more identities for HL students

Want a deeper conceptual understanding? Try our interactive lesson! (Plus Only)

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Practice exam-style trigonometric identities problems

Key Skills

sin²θ+cos²θ=1

SL 3.6

For any value of θ:

sin2θ+cos2θ=1📖

Sine Double Angle Identity

SL 3.6

The double angle identity for sin states that

sin2θ=2sinθcosθ📖

Cosine Double Angle Identity

SL 3.6

The double angle identity for cosine states that

cos2θ =cos2θ−sin2θ=2cos2θ−1=1−2sin2θ

These three different forms come from leveraging sin2θ+cos2θ=1.