Question

if cos(x)=-1/2. then what is the value of x?​

Answer 1

Answer:

Cos(120°)

Step-by-step explanation:

cos(x) =-1/2=cos -60°

cos60°=1/2

I. e cos(x) =-60°

I. e cos -60° = cos 120° in 2nd quadrant

I. e cos(x) = cos120°

I. e x=120°

Answer 2

Answer:

120 is the required value of x.

Step-by-step explanation:

Given, cos(x) =$\frac{-1}{2}$

We know that , -cos $\frac{\pi }{3}$ = $\frac{-1}{2}$

 ⇒ cos $[\pi -\frac{\pi }{3} ]$ = $\frac{-1}{2}$

⇒cos $\frac{2\pi }{3}$ = $\frac{-1}{2}$ ...........(i)

So, from the given question we have ,

cos (x) =  $\frac{-1}{2}$

Now put the value of $\frac{-1}{2}$  from equation (i)

Therefore ,

cos (x) = cos ($\frac{2\pi }{3}$)

⇒x = $\frac{2\pi }{3}$

Now we change the value of $\frac{2\pi }{3}$ in degree

so ,x = $\frac{2 .(180)}{3}$ = $\frac{360}{3}$ =120 °

Final answer :

Hence , the value of x is 120