Question

Is 100º coterminal with -1180º?

Answer 1

ANSWER

NO

EXPLANATION

If two angles are coterminal, then the two angles have the same terminal side in standard position.

So you can sketch both 100° and -1180° in standard position to see if they have the same terminal side.

A quicker way to do this is to keep adding 360° to -1180° to see if you will get 100°.

-1180°+360°=-820°

-1180°+360°+360°=-460°

-1180°+360°+360°+360°=-100°

-1180°+360°+360°+360°+360°=260°

Therefore the least positive angle that is coterminal with -1180° is 260°.

Hence 100° is not coterminal with -1180°

The answer is NO

Answer 2

Angles are coterminal if their difference is a multiple of 360 degrees.

100 - -1180 = 1280

1280 / 360 = 3.56

The difference is not a multiple of 360, so they are not coterminal.