Question

if cos x=5/13;
find the value ofsin x=?

Answer 1

Sin x =(1-cos^2x)^1/2

So sinx =12/13

Answer 2

Cos x = adj side/ hypotenuse 
sin x = Opp side / hypotenuse
draw a triangle and use Pythagoras theorem to find the opposite side
sin c = 12/13