Question

What value of x satisfies

cost (90 degrees -x)=-root 3 /3

A.
120°
B.
240°
C.
210°
D.
150°

Answer 1

the correct answer is 150

Explanation:

i j took the test

Answer 2

See explanation

Explanation:

The given trigonometric equation is
`cos(90-x)=-(√(3) )/(3)`.

We take the inverse cosine of both sides to get:

`90-x=cos^(-1)(-(√(3) )/(3))`

`90-x=125`

`x=125-90`

`x=-35\degree=325\degree` to the nearest degree

None of the options satisfies the given equation.

But if the question is actually;

`cos(90-x)=-(√(3) )/(2)`

Then;

`90-x=\cos^(-1)(-(√(3) )/(2))`.

`90-x=210`.

`90-x=210`.

`x=-120\degree`.

Or

`x=360-120=240\degree`.

In this case the answer will be B