Python - math.asin() method example

The math.asin function returns number in radians in the range -math.pi/2 to +math.pi/2. The function calculates the inverted sine function value.

import math


def calculate_angle(a, h):
    return math.asin(a / h)


#   |\
#   | \ h
# a |  \
#   |__*\ <- angle
#     b


# a, b and h build an isosceles right triangle
a = 3
b = a
h = math.sqrt(a * a + b * b)
print(calculate_angle(a, h))  # 0.7853981633974483 <-  45 degrees

# a, b and h build half of equilateral triangle
a = 3
b = a * math.sqrt(3)
h = math.sqrt(a * a + b * b)
print(calculate_angle(a, h))  # 0.5235987755982987 <- ~30 degrees

# a, b and h are not able to build triangle
a = 3
b = a
h = 1
print(calculate_angle(b, h))  # ValueError

1. Documentation

math.asin(number)

2. Working with degrees

import math


def calculate_angle(a, h):
    angle = math.asin(a / h)

    return (180 / math.pi) * angle


#   |\
#   | \ h
# a |  \
#   |__*\ <- angle
#     b


# a, b and h build isosceles right triangle
a = 3
b = a
h = math.sqrt(a * a + b * b)
print(calculate_angle(a, h))  # ~45 degrees

# a, b and h build half of equilateral triangle
a = 3
b = a * math.sqrt(3)
h = math.sqrt(a * a + b * b)
print(calculate_angle(a, h))  # ~30 degrees

# a, b and h are not able to build triangle
a = 3
b = a
h = 1
print(calculate_angle(b, h))  # ValueError

References

1. Inverse trigonometric functions - Wikipedia