Is there any engineers going to answer this math question, its important!

hey, i've asked this in mathematics 4 times, but didn't get any answers!
so i thought maybe you engineers can help me cause after all, you've studied a lot of mathematics!

Cosntheta?
sinntheta?
tngntheta?
cotntheta?

&

cos(theta1+theta2+theta3+...+thetan) , n ∈ N ?

What is the question exactly?

Maybe you have had no answers because you have not asked correctly. What do you want to know?