I've become stumped on these last two problems and would appreciate any and all help.

1)Find all the solutions in degrees to 21sin^{2}(theta)+10sin(theta)=-1. Round your answers to one decimal place.

2) Let pi < alpha < 3pi/2 ; pi/2 < beta < pi ; cos(alpha) = -4/9 ; sin(beta)= 7/12. Find the exact value for each of the following:

cos(alpha-beta)

sin(alpha+beta)

cos(alpha/2)

sin(2*alpha)

Thank you.