Need Help With This Trig's Question

Question

a. (tan(theta) +1)(cos(theta) +1)=0 

b. tan^-1(tan(3pi/8))

Answer 1

In a.set each of the factors equal to zero.

-pi/4 and pi will satisfy...and, of course, there are other roots because of periodicity

In b arc tan is the inverse of tan and the answer is 3 pi/8