# L'Hospitals Rule

1. Oct 16, 2008

### Tubig

lim (x approaches 9pi/4) (tanx)^tan10x

use L'Hospital's Rule to find the exact value

my attempt:
y = lim (tanx)^tan10x
lny= lim ln(tanx)^tan10x
= tan10x lim ln(tanx)

I really don't know where to go from there

-Thanks

2. Oct 16, 2008

### cellotim

In your last line, you take tan10x out of the limit without evaluating it. Put it back in and turn it into cot(10x) to put it on the bottom, then apply L'Hospital's. Make sure to apply exp at the end to get the final answer.