SOLUTION: Limx>0 xtanx/1-cosx

Algebra ->  Customizable Word Problem Solvers  -> Geometry -> SOLUTION: Limx>0 xtanx/1-cosx      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


   



Question 847230: Limx>0 xtanx/1-cosx
Answer by swincher4391(1107) About Me  (Show Source):
You can put this solution on YOUR website!
lim %28x%2Atan%28x%29%29%2F%281-cos%28x%29%29
x->0
using l'hopital's rule:
derivative of numerator [use product rule] = x *sec^2(x) + tan(x)
derivative of denominator = sin(x)
plugging in 0 to numerator = 0
plugging in 0 to denominator = 0
Use L'hopital's rule again
derivative of new numerator [use product rule] = (2x*tan(x)+1)sec^2(x) + x*sec^2(x) + tan(X) = 2(xtan(x) + 1)*sec^2(x)
derivative of new denominator = cos(x)
plugging in 0 into numerator = 2 * 1 = 2
plugging in 0 into denominator = 1
So the limit is 2/1 = 2.