Trig

cosθ 90°

0

sinθ 0°

0

tanθ 0°

0

cosθ 0°

1

sinθ 90°

1

tanθ 45°

1

cosθ 60°

1/2

sinθ 30°

1/2

Negative θ (clockwise)

Add 360° until θ is positive, once θ is positive use the reference guide.

QI

sin + cos + tan +

QII

sin + cos - tan -

QIV

sin - cos + tan -

QIII

sin - cos - tan +

If θ ∈ QII

then the reference angle (theta hat) = 180°-θ

If θ ∈ QIII

then the reference angle (theta hat) = θ-180°

If θ ∈ QIV

then the reference angle (theta hat)=360°-θ

If θ ∈ QI

then the reference angle(theta hat) = θ

tanθ 90°

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cosθ 45°

√2/2

sinθ 45°

√2/2

tanθ 60°

√3

cosθ 30°

√3/2

sinθ 60°

√3/2

tanθ 30°

√3/3