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## Convert angle to radians

To convert an angle expressed in ** degrees ** (30 °, 90 °, etc.) to ** radians ** (π/6, π/4, etc.) Use the ** deg2rad ** function of the Math::Trig module. To do the opposite, use the ** rad2deg ** function.

use Math::Trig 'pi', 'deg2rad'; # Convert the degree angle to the radian angle my $rad = deg2rad(30); # Convert radian angle to degree angle my $deg = rad2deg (pi/6);

Trigonometric functions are explained in detail on the following pages.

### Degree method and radian method

The degree method is a method of expressing an angle that uses a circle divided into 360 as a unit. Expressions of angles that you often see 30 °, 90 °, etc. are angles expressed in degrees.

On the other hand, the radian method is a method of expressing an angle in units of the central angle of a sector whose radius is r and whose circumference is r. 180 ° in degrees is π in radians. Keeping this in mind, 30 ° is one sixth of 180 °, so we can find that it is equal to π/6.

# !/usr/bin/perl use strict; use warnings; use Math::Trig qw/pi deg2rad rad2deg/; print "(1) Convert angles to radians.\n"; print deg2rad(30) . "\n"; print "(2) Convert radians to angles.\n"; print rad2deg (pi/6) . "\n";