find the limt #2

Calculus Level 2

lim x π 4 sin x cos x ln ( cot x ) = ? \lim_{x \to \frac \pi 4} \frac {\sin x - \cos x}{\ln (\cot x)} =\ ?


The answer is -0.7071.

This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try refreshing the page, (b) enabling javascript if it is disabled on your browser and, finally, (c) loading the non-javascript version of this page . We're sorry about the hassle.

2 solutions

Chew-Seong Cheong
Jul 14, 2020

L = lim x π 4 sin x cos x ln ( cot x ) A 0/0 case, L’H o ˆ pital’s rule applies. = lim x π 4 cos x + sin x tan x cot x Differentiate up and down w.r.t. x = 2 2 0.707 \begin{aligned} L & = \lim_{x \to \frac \pi 4} \frac {\sin x - \cos x}{\ln (\cot x)} & \small \blue{\text{A 0/0 case, L'Hôpital's rule applies.}} \\ & = \lim_{x \to \frac \pi 4} \frac {\cos x + \sin x}{-\tan x - \cot x} & \small \blue{\text{Differentiate up and down w.r.t. }x} \\ & = - \frac {\sqrt 2}2 \approx \boxed{-0.707} \end{aligned}


Reference: L'Hôpital's rule

thanks sir nice

Aly Ahmed - 11 months ago

Log in to reply

Glad that you like it.

Chew-Seong Cheong - 11 months ago

Transforming the variable from x x to h = π 4 x h=\frac{π}{4}-x and applying L'Hospital's rule we get the value of the limit as

2 × 1 2 = 1 2 = 0.7071 -\sqrt 2 \times \dfrac {1}{2}=-\dfrac {1}{\sqrt 2 }=\boxed {-0.7071} .

thanks sir

Aly Ahmed - 11 months ago

0 pending reports

×

Problem Loading...

Note Loading...

Set Loading...