how do you solve this exactly? i get pi/4 and 5pi/4 by looking at a graph?

Question is solve over the set of real numbers

2sin^x-5sinx-3

I factored and got

{2sinx+1}{sinx-3}

sinx cant = 3 so

sinx = -1/2

answer is 7pi/6+2n, 11pi/6+2n n is an interger ?

If I use my calc I get the decimal answer right but how do I do this?