Equation of the tangent to a curve

[Jan Hill]

Homework Statement

y = secx
find the equation of the tangent to the curve at x = -9pi/4 and -7pi/4

Homework Equations

the derivative is secxtanx. do I just subsitute in the values -9pi/4 and then -7pi/4 to get the answer to the slope then what?

The Attempt at a Solution

 

[fzero]

If you know the slope of the line, you can find the intercept once you know at least one point on that line.