Question

If sinx=-4/5 and x lies in the 3rd quadrant then the value of cosx/2 is.

Answer 1

Answer:

Step-by-step explanation:

since x lies in the third quadrant cosx is negative

cosx=-3/5

cosx/2=√1+cosx/2

           =√1-3/5*2

           =1/√2

Answer 2

Answer:

$\frac{2}{\sqrt{5} }$

Step-by-step explanation:

sinx=-4/5

$cos^{2} x$=$1-sin^{2}x$

        = 1 - $(-4/5)^{2}$

        = 1 -($\frac{16}{25}$)

        =$\frac{9}{25}$

 cosx=$\sqrt9/25$

cosx=3/5

$cos^{2} \frac{x}{2}$ =  $\frac{1+cosx}{2}$

         = $\frac{1-\frac{3}{5} }{2}$

    =  $\frac{\frac{8}{5} }{2}$

       = $\frac{4}{5}$

$cos^{} \frac{x}{2}$ = $\sqrt{} \frac{4}{5}$

       = 2/$\sqrt{5}$