Guys i really need with part c) i literally have no idea how to this. given that tan(pi/8)=sqrt(2)-1. i am really looking forward to step-by-step explanation.

Step-by-step explanation:

This equation is more intimidating than the problem you have to solve.

You know that the sine of everything is always between -1 and +1. So for the entire expression to be >= 0, the a*tan(pi/8) bit has to be 1 at least. Given this, we can forget about the sin(...) term of the equation for the remainder of solving it.

You already figured out that tan(pi/8) is sqrt(2)-1.

So what we're saying is a * (sqrt(2) - 1) has to be 1 at least.

If we solve a(sqrt(2)-1) >= 1 for a we get:

a = 1/(sqrt(2)-1)

dont understand

step-by-step explanation: