Question

Howdy! Id love to have these questions answered asap! Thank you for the help!

1) Which angle is not coterminal to 120 degrees?
A. 840
B. -180
C. 480

2) Use the unit circle and the reference angle to determine which of the following trigonometric values is correct when theta = -90
A. Cos theta = undefined
B. Sin theta = -1
C. Tan = 0

Answer 1

1. B.

2. B.

Explanation:

Trigonometry

1) Coterminal angles can be found by adding or subtracting 360° (or 2\pi radians) to a given angle. If we have 120°, adding 360° gives 480°, adding again 360° gives 840°. There is no way to get -180°, so this option is not a coterminal angle to 120°

2)

A.
`Cos (-90^o)=0`, and not undefined

B.
`Sin (-90^o)=-1`. This is correct

C.
`Tan (-90^o)` is undefined, not zero

Thus the only correct option is B.