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Python - math.asin() method example

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Created by:

Nataniel-Barclay

499

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.

xxxxxxxxxx
 
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

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Syntax	xxxxxxxxxx 1 math.asin(number)
Parameters	`number` - double value that represents the result of the operation `adjacent / hypotenuse` on the right triangle. `number` should be in the range `-1` to `+1`.
Result	`number` value in radians in the range `-math.pi/2` to `+math.pi/2`. If the value can not be calculated `ValueError` occurs.
Description	`asin` is a method that takes only one parameter and returns an approximation of the result of the mathematical function arcsine(x).

2. Working with degrees

Edit

xxxxxxxxxx
 
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