Question

-120 degrees is equal to what?

Answer 1

It's not clear what you're looking for.

If you want to find an angle whose terminal point involves a positive angle, then -120 degrees is equivalent to +240 degrees.

If you want the equivalent angle in radians, then:

-120 deg        -π rad

-------------- = --------------- =  - 2π/3 rad, or + 4π/3 rad.

      1              180 deg

Answer 2

-120 degrees equals 240 degrees by unit circle. Also we can find it by knowing that a circle is 360° and just adding -120° + 360° and that equals 240 degrees.

ALSO,
$( - 120) \times \frac{\pi}{180} = - \frac{2\pi}{3}$
So, -120° is -2pi/3 radians, so we can do the same thing, but just in a relation to radians, so we know 360° equals 2pi, but if we don't we can find it

$( 360) \times \frac{\pi}{180} = {2\pi}$
So,
$- \frac{2\pi}{3} + 2\pi = \frac{4\pi}{3}$
Now,
$\frac{4\pi}{3} \times ( \frac{180}{\pi} ) also \: equals \: 240$


Answer:

$\frac{4\pi}{3} \: or \: 240 \: degrees$