Tangent equation provide wrong output

Question

I cannot seem to find a solution to my math problem in Python, no article fits the issue. Do believe it may resides in a structural setup, but frankly I am out of options based on my knowledge. Have tried to read the library, but it too does not provide an solution.

Simply what is happening is this:

Code runs fine, except the output is wrong.

import math

descent_speed = float(150 * (1/60) * 6080 * (math.tan(3.0)))
print(descent_speed)

Results: -2166.7074547290226

Now the correct answer to the calculation of

150 = Ground Speed in knots 3.0 = Angle of descent path in degrees

150 * 1/60 * 6080 * tan(3.0) = 796.5982451

That is according to the calculator which equals to 797 feet per minute.

Now I did try adding 3.0 as a degree using math.degrees, but that did not work.

import math

GS = 150
slope = math.degrees(3.0)
descent_speed = float((GS) * (1/60) * 6080 * (math.tan(slope))) #code to calculate descent speed based on descent angle
print(descent_speed)

Results: -19164.534008140585

So please help, I am out of ideas?

Answer 1

Trigonometric functions take their inputs in radians. Change math.degrees to math.radians :

>>> help(math.tan)
Help on built-in function tan in module math:

tan(x, /)
    Return the tangent of x (measured in radians).

>>> angle_in_degrees = 3.0
>>> 150 * (1/60) * 6080 * math.tan(math.radians(angle_in_degrees))
796.5982451022264