Calculus
posted by Z32 .
If the equation of the tangent line to the curve y=9cosx
at the point on the curve with xcoordinate 3pi/4 is written in the form y=mx+b then m=? and b=?

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. 
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. 
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.