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04/20/23 7By Chtan FYHS-Kulai
Now, if you flip the previous graph,
x
y
02
2-
xy -1sin
1
-1Principal valuesThe principal values of y is defined as that value lying between .
2
04/20/23 8By Chtan FYHS-Kulai
Similarly, check the cosine graph
x
y1
-1
0 2
2-
-
xy cos In this region, ,y is 1-1 function.
x0
04/20/23 9By Chtan FYHS-Kulai
Now, if you flip the previous graph,
x
y
2
2- 1
-1 0
Principal valuesThe principal values of y is defined as that value lying between 0 and ∏ .
xy -1cos
04/20/23 11By Chtan FYHS-Kulai
Graph of xy 1tan
x
y
2
2-
0
xy -1tan
Principal valuesThe principal values of y is defined as that value lying between .
2
04/20/23 12By Chtan FYHS-Kulai
Some books write as .
Domain of y is
Range of y is
xy -1sinxy arcsin
1,1
2,2
04/20/23 20By Chtan FYHS-Kulai
Now, let see Same as .
Domain of y is
Range of y is
xy -1cosxy arccos
1,1
,0
04/20/23 By Chtan FYHS-Kulai 23
e.g. 5
Evaluate .
1800 andSoln :Between
gives .
2
3-sin 1
6
5cos150cos
or
2
3
04/20/23 24By Chtan FYHS-Kulai
Now, let see Same as .
Domain of y is
Range of y is
xy -1tanxy arctan
,
22-
,
04/20/23 25By Chtan FYHS-Kulai
Now, let see Same as .
Domain of y is
Range of y is
xy -1cotxarcy cot
,
,0
04/20/23 By Chtan FYHS-Kulai 28
e.g. 7Evaluate .
5
4sincos 1
Soln :Let
5
4sin 1
5
4sin
3
54
5
3cos
5
4sincos 1
04/20/23 By Chtan FYHS-Kulai 29
e.g. 8Find the value of the following Expression :
2
1cos
5
3sinsin 11
04/20/23 By Chtan FYHS-Kulai 33
Soln : Let 2tan,3tan 11 ba
2tan3tan banda
ba
baba
tantan1
tantantan
161
5
04/20/23 By Chtan FYHS-Kulai 34
There are 2 possible answers.
135451tan 1 or
4
3135
orba
[because a and b are both positive values, a+b must be positive value.]
04/20/23 By Chtan FYHS-Kulai 38
Let prove the identity #1
To prove :2
cossin 11 xx
Same as to prove :
xx 11 cos2
sin
A
04/20/23 By Chtan FYHS-Kulai 39
LHS of A : xx 1sinsinCheck slide #14
RHS of A : xxx
11 coscoscos2
sin
xx 11 cos2
sinsinsin
We have,
and
2sin
2- 1-
x
x-1cos0 [ x(-1) ]
B
04/20/23 By Chtan FYHS-Kulai 40
0-cos- -1 x
02
cos-2
-2
1-
x
2cos-
22- 1-
x C
B and C state that both and are .
x1sin
x1cos-2
2,2
04/20/23 By Chtan FYHS-Kulai 42
Let prove the identity #2
To prove :2
cottan 11 xx
Same as to prove :
xx 11 cot2
tan
A
04/20/23 By Chtan FYHS-Kulai 43
xx 1tantan
xxxc
11 cotcotot-2
tan
xxc 11 tantanot-2
tan
But 2
tan2
1 x
and x1cot0 [ x(-1) ]
04/20/23 By Chtan FYHS-Kulai 46
Soln :BA
4
1tan,
3
1tan 11
Let
then 4
1tan,
3
1tan BA
BA
BABA
tantan1
tantantan
11
7
41
31
1
41
31
04/20/23 By Chtan FYHS-Kulai 48
e.g. 11Prove that
3
2tan2
13
5cos 11
Soln :BA
3
2tan,
13
5cos 11
Let
LHS:13
5
13
5coscos 1
04/20/23 By Chtan FYHS-Kulai 49
RHS: B2cos3
2tan2cos 1
1cos2 2 B
B2
3
13
13
51
13
92
2,02,
BA
3
2tan2
13
5cos 11
04/20/23 By Chtan FYHS-Kulai 51
Do keep in mind :
Equation Range of solution
The only solution
x1sin
x1cos
x1tan
x1cot
2,2
,0
2,2
,0
sinx
cosx
tanx
cotx
04/20/23 By Chtan FYHS-Kulai 54
e.g. 14Solve the equation , assuming that all the inverse tangents are positive acute angles.
2tan2tantan 111 xx
04/20/23 By Chtan FYHS-Kulai 55
Soln : 2tantan2tantantan 111 xx
Let xBxA 2tan,tan 11
2tantan1
tantan
BA
BA
xBxA 2tan,tan
04/20/23 By Chtan FYHS-Kulai 58
Differentiation of an inverse function :
If 53)( xxfy
then 3dx
dy
The inverse function is : xy 35
3
5y
x
04/20/23 By Chtan FYHS-Kulai 60
So, in general, )(xfy
0)(' xf)(1 yfx is the inverse
function of )(xfy
dxdydy
dx 1
04/20/23 By Chtan FYHS-Kulai 61
Differentiation of an inverse circular function :
xy 1sin 1,1x
Its inverse function :
yx sin
2,2
y
04/20/23 By Chtan FYHS-Kulai 64
Another way to derive this formula :
xy 1sin yx sin
ydx
dx
dx
dsin
dx
dyy
dy
dsin1
04/20/23 By Chtan FYHS-Kulai 67
e.g. 153
sin 1 xy
Find the differentiation of y.Soln :
3
31
12
x
dx
d
xdx
dy
29
1
x
04/20/23 By Chtan FYHS-Kulai 68
e.g. 16Find dy/dx if .
x
xy
1
1tan 1
Soln :
x
x
dx
d
xxdx
dy
1
1
11
1
12
04/20/23 By Chtan FYHS-Kulai 72
In a general format :(1)
ca
x
xa
dx
1
22sin
(2)
ca
x
axa
dx
1
22tan1
04/20/23 By Chtan FYHS-Kulai 73
e.g. 17Evaluate . 241 x
dx
Soln :
22
414
1
41 x
dx
x
dx
2
2
214
1
x
dx
04/20/23 By Chtan FYHS-Kulai 76
This type of integral can always be reduced to one of the three standard forms :
, , 22 xa
dx 22 xa
dx 22 ax
dx
04/20/23 By Chtan FYHS-Kulai 77
e.g. 18Evaluate . 2232 xx
dx
Soln :
2
2
23
12232
xx
dx
xx
dx
2
23
12
1
xx
dx
04/20/23 By Chtan FYHS-Kulai 84
e.g. 21
Evaluate .
64
)12 xx
dxx(
Soln :
64
12
64
)122 xx
dxx
xx
dxx(
6464
222 xx
dx
xx
dxx