For the first one, rewrite the equation using the double-angle identity for sine, to get:
Now, divide through by then subtract from both sides, factor and use the zero-factor property to equate both factors to zero and solve.
For the second one, use a Pythagorean identity to get a quadratic in :
Now, distribute, and arrange in standard quadratic form, and you will find it factors nicely, and use the zero-factor property to equate both factors to zero and solve.
James this is very easy
for the first remember that sin(2x) =2sinxcosx
transfer to the frst term and factorize to find
cosx =0 and sinx=sqrt(2)/2 solve them .....
for the second substitute cos^2(x) =1-sin^2(x) and solve the quadratic equation that you will obtain for sinx ..it is easy