SLIDESMANIA.COM
Title Here
Title Here
Title Here
Title Here
Title Here
Title Here
Title Here
Title Here
Limits Involving
Trigonometric Functions
SLIDESMANIA.COM
Learning Objectives:
Find the limits involving trigonometric
functions using appropriate theorems.
SLIDESMANIA.COM
Title Here Title Here
Title Here
Title Here
Title Here
Title Here
Review
REview
SLIDESMANIA.COM
Review
SLIDESMANIA.COM
The techniques and rules for finding limits
discussed in the previous lessons apply to the
trigonometric and exponential functions as well
as to algebraic functions.
1. lim
𝑥→0
sin 𝑥
𝑥
=
𝑥
𝑠𝑖𝑛 𝑥
= 1
2. lim
𝑥→0
1−cos 𝑥
𝑥
= 0
SLIDESMANIA.COM
Title Here Title Here
Title Here
Title Here
Title Here
Title Here
1.Find the lim
𝑥→
𝜋
4
sin 𝑥
𝑐𝑜𝑠𝑥
Example
Title Here
lim
𝑥→
𝜋
4
sin 𝑥
𝑐𝑜𝑠𝑥
= lim
𝑥→
𝜋
4
sin
𝜋
4
cos
𝜋
4
=
2
2
∙
2
2
= 1
SLIDESMANIA.COM
Example
lim
𝑥→0
1 − cos 𝑥
𝑠𝑖𝑛 𝑥
∙
1 + cos 𝑥
1 + cos 𝑥
=
1−cos2 𝑥
(sin 𝑥) ( 1+cos 𝑥)
=
sin2 𝑥
(sin 𝑥) ( 1+cos 𝑥)
=
(sin 𝑥) (sin 𝑥)
(sin 𝑥) ( 1+cos 𝑥)
=
(sin 𝑥)
(1+cos 𝑥)
Therefore,
lim
𝑥→0
1−cos 𝑥
𝑠𝑖𝑛 𝑥
= =
(sin 𝑥)
(1+cos 𝑥)
=
0
1+1
= 0
(rationalize)
Find the lim
𝑥→0
1 − cos 𝑥
𝑠𝑖𝑛 𝑥
SLIDESMANIA.COM
Title Here
Title Here
Title Here
Title Here
Title Here
= lim
𝑥→0
sin 3𝑥
𝑥
= 3 lim
𝑥→0
sin 3𝑥
3𝑥
= 3 ( 1)
= 3
Example
Title Here
Find the lim
𝑥→0
sin 3𝑥
𝑥
Note that :
lim
𝑥→0
sin 𝑥
𝑥
=
𝑥
𝑠𝑖𝑛 𝑥
= 1
We can factor out the 3 from
inside the sine function to
make the argument of the sine
function match the standard
form.
Example
SLIDESMANIA.COM
Title Here
Title Here
Title Here
Example
Title Here
Find the lim
𝑥→0
3𝑥 tan 𝑥
sin 𝑥
= lim
𝑥→0
3 0
cos 0
= 0
= lim
𝑥→0
3𝑥 sin 𝑥
cos 𝑥 sin 𝑥
SLIDESMANIA.COM
𝐹𝑖𝑛𝑑 𝑡ℎ𝑒 lim
𝑥→𝜋
cos 𝑥
𝑥2
= lim
𝑥→𝜋
cos 𝜋
𝑥2
=
−1
𝜋2
Example
Note :
𝜋 = 180 in
degree
SLIDESMANIA.COM
Example
lim
ℎ→3
sin( ℎ − 3)
ℎ2 + 2ℎ − 15
= lim
ℎ→3
sin( ℎ−3)
ℎ+5 ( ℎ−3)
( 𝑓𝑎𝑐𝑡𝑜𝑟𝑖𝑛𝑔)
= lim
ℎ→3
1
ℎ+5
∙
sin( ℎ−3)
ℎ−3
=
1
3+5
∙ 1
=
1
8
NOTE:
SLIDESMANIA.COM
Example
lim
ℎ→
𝜋
4
8𝑥 tan 𝑥 − 2𝜋 tan 𝑥
4𝑥 − 𝜋
= lim
ℎ→
𝜋
4
2 tan 𝑥 [ 4𝑥−𝜋]
4𝑥− 𝜋
lim
ℎ→
𝜋
4
2 tan 𝑥 [ 4𝑥−𝜋]
4𝑥− 𝜋
( 𝑎𝑝𝑝𝑙𝑦𝑖𝑛𝑔𝑓𝑎𝑐𝑡𝑜𝑟𝑖𝑛𝑔 𝑐𝑜𝑚𝑚𝑜𝑛 𝑚𝑜𝑛𝑜𝑚𝑖𝑎𝑙 𝑓𝑎𝑐𝑡𝑜𝑟)
= lim
ℎ→
𝜋
4
2 tan 𝑥
= 2tan
𝜋
4
= 2 (1)
SLIDESMANIA.COM
Title Here
Title Here
Example
Title Here
SLIDESMANIA.COM
Example
SLIDESMANIA.COM
SLIDESMANIA.COM
Example
NOTE:
SLIDESMANIA.COM
Continuation
SLIDESMANIA.COM
Title Here
Let’s Try
Title Here
SLIDESMANIA.COM
Title Here
Title Here
1. lim
𝑥→
𝜋
2
cot 𝑥
2. lim
𝑥→
𝜋
4
3 tan 𝑥 + 1
3. lim
𝑥→0
sin 5𝑥
𝑥
4. lim
𝑥→0
tan 𝑥
4𝑥
5. lim
𝑥→0
sin 5𝑥
sin 6𝑥
Determine the value of each limits if it exist.
6. lim
𝑥→1
sin( 𝑥2−1)
𝑥−1
7. lim
𝑥→11
cos( 𝑥−7)
𝑥2−16𝑥+63
•
1
5𝑥
8. lim
𝑥→0
cos2 𝑥 −cos(𝑥)
cos(𝑥)−1
9. lim
𝑥→2
sin( 2𝑥−4)
5𝑥 −10
SLIDESMANIA.COM
Title Here
THANK YOU!
SLIDESMANIA.COM
References:
https://mathrescue.blogspot.com/2012/03/trigonometry-
proving-trigonometric.html
chrome-
extension://kdpelmjpfafjppnhbloffcjpeomlnpah/https://www.math.utah.edu
/lectures/math1210/5PostNotes.pdf
https://www.mathdoubts.com/evaluate-limit-sin5x-sinx3x-divided-by-
x-as-x-approaches-to-0/

Limits-Involving-Trigonometric-Functions.pdf