Trigonometric Functions Table
The trigonometric functions (also called the circular functions) are functions of an angle. They relate the angles of a triangle to the lengths of its sides.
Returns  Input  
Inverse cosine 
Angle in radians 
ARCCOS(w) 
w =adjacent/hypotenuse 
Inverse cotangent 
ARCCOT(w) 
w =adjacent/opposite 

Inverse cosecant 
ARCCSC(w) 
w =hypotenuse/opposite 

Inverse secant 
ARCSEC(w) 
w =hypotenuse/adjacent 

Inverse sine 
ARCSIN(w) 
w =opposite/hypotenuse 

Inverse tangent 
ARCTAN(w) 
w =opposite/adjacent 

Inverse tangent 
ATN(w) 
w =opposite/adjacent 

Cosine  adjacent/hypotenuse 
COS(r) 
r =angle in radians 
Cosecant  hypotenuse/opposite 
CSC(r) 

Secant  hypotenuse/adjacent 
SEC(r) 

Sine  opposite/hypotenuse 
SIN(r) 

Tangent  opposite/adjacent 
TAN(r) 
All of the angles used in these functions are based on radians instead of degrees (π radians = 180°).
A very good approximation of π which I find easy to remember is 355 / 113 (and more accurate than the more commonly used 22 / 7 approximation). Note that it is 113355 split in the middle and switched around to create a ratio.
So if you have degrees, you can use the following formula.
degrees / 180 * 355 / 113 = radians
Which is the same as:
355 * degrees / 20340 = radians
Converting back can be done by switching around the division and multiplication.
radians * 180 / 355 * 113 = degrees
Which is the same as:
20340 * radians / 355 = degrees