If the equation of the tangent line to the curve y=9cosx

Question

at the point on the curve with x-coordinate 3pi/4 is written in the form y=mx+b then m=? and b=?

Answer 1

m is the slope of the tangent,
m= d/dx (9cosx)=-9sinx
you are given x, so you can compute m.

then, knowing x,y, put that into y=mx+b to solve for b.

Answer 2

x would be 3pi/4 correct?

What would 3pi/4 equal approximately? I tried to do -9 * sin * 3pi/4 but I'm not getting the correct answer.

Answer 3

3pi / 4 is a memory value (use the 45 - 45 - 90 right triangle). If you're not getting the correct answer inputting it into a calculator, you may be in degree mode.