(c)
\The given value
.
Step 1 :
\From cosine function
\Hypotenuse = 4
\Adjacent = - √6
\From Pythagorean theorem
\



Formula for sine function : 

Step 2 :
\To find value of sin(θ/2)
\Apply half angle of sine function formula : 
Substitute
in above formula

Rewrite the expression with common denominator.
\

Solution :
\