Here are

sixteen Trigonometric Identities:

SIN = Sine
COS = Cosine
TAN = Tangent
CSC = CoSecant
SEC = Secant
COT = CoTangent
**
#1
1
SIN Θ = -----
CSC Θ
#2
1
COS Θ = -----
SEC Θ
#3
SIN Θ
TAN Θ = -----
COS Θ
#4
COS Θ 1
COT Θ = ----- = -----
SIN Θ TAN Θ
#5
1
SEC Θ = -----
COS Θ
#6
1
CSC Θ = -----
SIN Θ
#7
SIN**^{2} Θ + COS^{2} Θ = 1
#8
SEC^{2} Θ = 1 + TAN^{2} Θ
#9
CSC^{2} Θ = 1 + COT^{2} Θ
#10
SIN^{2} Θ = ½ ( 1 - COS 2Θ )
#11
COS^{2} Θ = ½ ( 1 + COS 2Θ )
#12
SEC^{2} Θ = 1 + TAN^{2} Θ
#13
CSC^{2} Θ = 1 + COT^{2} Θ
#14
SIN Θ COS Θ = ½ SIN 2Θ
#15
COS 2Θ = COS^{2} Θ - SIN^{2} Θ
#16
2 TAN Θ
TAN 2Θ = ----------
1 - TAN^{2} Θ

These

trigonometric identities are particularly useful in the

electronics

field.