# Finding normal and tangent of a curve

• October 14th 2009, 03:38 PM
Finding normal and tangent of a curve
Ok, i generally know how to find a tangent and it's normal by applying the f(a+h)+f(a)/h formula, but this equation apparently has tan(trig) and I have no idea how to deal with it:
y=2tan(pix/4) at x =1
Please explain to me how you get your answer thank you.
• October 14th 2009, 03:50 PM
skeeter
Quote:

Originally Posted by maximade
Ok, i generally know how to find a tangent and it's normal by applying the f(a+h)+f(a)/h formula, but this equation apparently has tan(trig) and I have no idea how to deal with it:
y=2tan(pix/4) at x =1
Please explain to me how you get your answer thank you.

are you aware of the general formula for the derivative of the tangent function ?

$\frac{d}{dx} \tan{u} = \sec^2{u} \cdot \frac{du}{dx}$

finding the value of the derivative using the limit definition is going to be a bit long and overwhelming algebra-wise.