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Module 2: Quick Reference Card
The Unit Circle & Right Triangle Trig
Unit Circle Special Values
θ
0
π/6
π/4
π/3
π/2
sin
0
1/2
√2/2
√3/2
1
cos
1
√3/2
√2/2
1/2
0
tan
0
√3/3
1
√3
undef
Sign Rules (ASTC)
QI: All + | QII: Sin +
QIII: Tan + | QIV: Cos +
sin²θ + cos²θ = 1
Reference Angles
QI: θ' = θ
QII: θ' = π − θ
QIII: θ' = θ − π
QIV: θ' = 2π − θ
SOH-CAH-TOA
sin = Opp/Hyp
cos = Adj/Hyp
tan = Opp/Adj
Reciprocals
csc = 1/sin = Hyp/Opp
sec = 1/cos = Hyp/Adj
cot = 1/tan = Adj/Opp
Cofunctions
sin θ = cos(90°−θ) | tan θ = cot(90°−θ) | sec θ = csc(90°−θ)