Calculate x → 2 π lim ( x tan x − 2 π tan x )
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.
With out L 'Hôpital's rule
Y = x tan ( x ) − ( π / 2 ) tan ( x )
= ( x − π / 2 ) tan ( x )
= ( x − π / 2 ) cot ( π / 2 − x )
= [ ( x − π / 2 ) × cos ( π / 2 ) ] / ( sin ( π / 2 − x ) )
As
x
reaches to
(
π
/
2
)
sin
(
π
/
2
−
x
)
=
(
π
/
2
−
x
)
So the Y becomes ( x − π / 2 ) / ( π / 2 − x ) × cos ( π / 2 − x )
= − 1 × cos ( z ) (where z reaches to zero)
= − 1 × 1 = − 1
how come when x reaches 2 π , sin ( 2 π − x ) = 2 π − x ?
Log in to reply
s i n ( π / 2 − x ) = ( π / 2 − x ) (here (π/2-x ) reaches to zero)
For small angles. S i n ( z ) = z (here z reaches to 0)
Problem Loading...
Note Loading...
Set Loading...
L = x → 2 π lim ( x tan x − 2 π tan x ) = x → 2 π lim ( x − 2 π ) tan x = x → 2 π lim cot x x − 2 π = x → 2 π lim − csc 2 x 1 = − 1 A 0/0 case, L’H o ˆ pital’s rule applies Differentiate up and down w.r.t. x .
Reference: L'Hôpital's rule