Question

My python interpreter is acting funky when I use the math.cos() and math.sin() function. For example, if I do this on my calculator:

cos(35)*15+9 = 21.28728066
sin(35)*15+9 = 17.60364655

But when I do this on python (both 3.2 and 2.7)

>>> import math
>>> math.cos(35)*15+9
-4.5553830763726015

>>> import math
>>> math.sin(35)*15+9
2.577259957557734

Why does this happen?

EDIT: How do you change the Radian in Python to degrees, just in case?

Answer 1

This is being caused by the fact that you are using degrees
and the trigonometric functions expect radians as input:
sin(radians)

The description for sin is:

sin(x)
    Return the sine of x (measured in radians).

In Python, you can convert degrees to radians with the math.radians function.

So if you do this with your input:

>>> math.sin(math.radians(35)) * 15 + 9
17.60364654526569

it gives the same result as your calculator.