问题
I'm trying to find out the angle of the triangle in the following, I know it should be 90 degrees, however I don't know how to actually calculate it in the following:
Here's what I've tried:
angle = math.cos(7/9.899)
angleToDegrees = math.degrees(angle)
returns: 43.XX
What am I doing wrong?
回答1:
It's a little more compicated than that. You need to use the law of cosines
>>> A = 7
>>> B = 7
>>> C = 9.899
>>> from math import acos, degrees
>>> degrees(acos((A * A + B * B - C * C)/(2.0 * A * B)))
89.99594878743945
This is accurate to 4 significant figures. If you provide a more precise value of C, you get a more accurate result.
>>> C=9.899494936611665
>>> degrees(acos((A * A + B * B - C * C)/(2.0 * A * B)))
90.0
回答2:
i think you're looking for math.acos not math.cos, you want to return the angle whose value is the ratio of those two sides. not take its cosine.
回答3:
Trig functions will convert an angle into a length of a certain leg of a certain triangle. In particular, the tangent is the ratio of the opposite side to the adjacent side. math.tan(7/7) is the length of the right triangle opposite an angle of 1(=7/7) radian. This length (~1.557) just happens to be near to the number of radians which is 90 degrees (pi/2 ~ 1.571).
As noted, you're looking for an inverse trig function to convert a length back into an angle.
回答4:
use this:
import math
AB = float(input())
BC = float(input())
print(str(int(round(math.degrees(math.atan2(AB, BC)))))+'°')
回答5:
You can use this also.
print(str(int(round(math.degrees(math.atan2(x,y)))))+'°')
This accepts two inputs as two heights of the triangle and you can get the output angle in proper degree format.
来源：https://stackoverflow.com/questions/18583214/calculate-angle-of-triangle-python