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Chapter 4: D. Basic Trigonometry 29
Table 4.1 Calculation of trigonometric functions.
Function Example Formula
Sine
a
B
c
sin ( a
A )= opposite side
hypotenuse
= c
Part I.D
90°
C
b
A
Cosine
B
cos A
adjacent side
hypotenuse
( ) =
b
c
a
c
90°
C
b
A
Tangent
a
B
90°
c
opposite side a
tan( A)= =
adjacent side b
( )
( )
sin A
=
cos A
C
b
A
Cotangent
a
B
90°
c
adjacent side b
cot( A)= =
opposite side a
1
=
tan A
(
( )
) = cos A
sin( A)
C
b
A
Secant
a
B
90°
c
hypotenuse c
sec( A)= =
adjacent side b
1
=
cos A
( )
C
b
A
Cosecant
a
B
90°
c
hypotenuse c
csc( A)= =
opposite side a
1
=
sin A
( )
C
b
A