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Trig Identities Verifier
AP Precalculus · Unit 3 Trigonometric Functions
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Learning Objectives
Verify Pythagorean identities graphically
Confirm double-angle and sum formulas visually
Understand cofunction and reciprocal relationships
Fundamental Identities
\(\sin^2\theta + \cos^2\theta = 1\)
\(1 + \tan^2\theta = \sec^2\theta\)
\(\sin(2\theta) = 2\sin\theta\cos\theta\)
\(\cos(2\theta) = \cos^2\theta - \sin^2\theta\)
\(\sin(\alpha+\beta)=\sin\alpha\cos\beta+\cos\alpha\sin\beta\)
Tags
trig identities
Pythagorean
double angle
sum formula
AP Precalculus
Identity
sin²θ + cos²θ
Status
✅ Verified
Select Identity
sin²+cos²=1
1+tan²=sec²
sin(2θ)=2sinθcosθ
cos(2θ)=cos²−sin²
sin(−θ)=−sinθ
cos(−θ)=cosθ
tan=sin/cos
sin(π/2−θ)=cosθ
Verification
✅ IDENTICAL
Both sides overlap at every point — identity confirmed.
Legend
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Left Side (LHS)
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Right Side (RHS)
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Difference (should be 0)
Quick Quiz
Which identity is equivalent to cos(2θ)?
2cosθ
1 − 2sin²θ
sin²θ + cos²θ
sinθcosθ