63,665 views
33 votes
33 votes
How do we find coterminal angles for
degrees? Radians?

User Pawel Wiejacha
by
2.5k points

2 Answers

25 votes
25 votes

Coterminal angles point in the same exact direction.

In degree mode, you can add on 360 degrees to get a coterminal angle.

Example: 90 degrees is coterminal to 450 degrees because 90+360 = 450. Both angles 90 and 450 point directly north.

You can also subtract 360 from the angle to get a coterminal counterpart.

Example: Given the angle 700, it is coterminal to 340 since 700-360 = 340

This process of adding or subtracting 360 can be done as many times as you like.

------------------------------

For radian mode, you'll add or subtract 2pi radians to get a coterminal angle. This is because 2pi radians = 360 degrees by definition.

Examples:

  • pi is coterminal to 3pi because pi+2pi = 3pi, both point directly west
  • pi/4 is coterminal to 9pi/4 because pi/4 + 2pi = pi/4 + 8pi/4 = 9pi/4
  • 21pi/4 is coterminal to 13pi/4 because 21pi/4 - 2pi = 21pi/4 - 8pi/4 = 13pi/4
User Steven Lockton
by
2.8k points
7 votes
7 votes

Answer:

To find coterminal angles, add or subtract 360 degrees of the terminal angle as many times possible.

To find radians, use this formula:

Degrees × π/180°

User Annyo
by
2.6k points