Evaluate (exact answers):

Question

a) sin^-1(cos30)

Need help. What do I do?

b) sin[(cos^-1((sqrt2)/(2)))+[(sin^-1((sqrt2)/(2)))]
= sin(45+45)
= sin90
= 1

Is this correct?

c) cos(arctan5/7)
= 7/(sqrt74)
= (7sqrt74)/74

Is this correct?

Please and Thank you!