082-Engineering-Mathematics-Anthony-Croft-Robert-Davison-Martin-Hargreaves-James-Flint-Edisi-5-2017

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438 Chapter 13 IntegrationSolution Powersoftrigonometricfunctions,forexamplesin 2 t,donotappearinthetableofstandardintegrals.Whatwemustattempttodoisrewritetheintegrandtoobtainastandardform.(a) FromTable 3.1cos 2 t = 1+cos2t2(b)and so∫ ∫ 1+cos2tcos 2 t dt = dt2∫ ∫ 1 cos2t=2 dt + dt2= t 2 + sin2t +c4∫ ∫sin 2 t dt = 1 −cos 2 t dt using the trigonometric identities∫=∫1dt−cos 2 t dt( t= t −2 + sin2t )+c4= t 2 − sin2t4+kusing linearityusing part(a)Example13.6 Find(a) ∫ sin2tcost dt(b) ∫ sinmtsinnt dt, wheremandnareconstants withm ≠nSolution (a) Usingthe identitiesinTable3.1 wefind2sinAcosB =sin(A +B) +sin(A −B)hence sin2tcost can bewritten 1 (sin3t +sint). Therefore,2∫∫ 1sin2tcost dt = (sin3t +sint)dt2= 1 ( )−cos3t−cost +c2 3= − 1 6 cos3t − 1 2 cost+c(b) Usingthe identity2sinAsinB = cos(A −B) −cos(A +B), we findsinmtsinnt = 1 {cos(m −n)t −cos(m +n)t}2

Therefore,∫∫ 1sinmtsinnt dt = {cos(m −n)t −cos(m +n)t}dt2= 1 { }sin(m −n)t sin(m +n)t− +c2 m −n m +n13.2 Elementary integration 439EXERCISES13.21 Integratethe following expressions usingTable 13.1:1 1(e) √ (f)(a) x 10 (b) 9 (c) x 1.50.25 −x 2 0.01 + v 2(d) √ 1 11(g)t (e) (f) −3.210 6 +r 2 (h)10+t 2z1 11 1(g)x 3 (h) √ (i) (x 2 ) 3(i) √ (j)t 2−x 2 1(j) x −2 (k) t 1/39 +x25 Integratethe followingexpressions:2 Integratethe following expressions usingTable 13.1:(a) e 5x (b) e 6x (c) e −3t (a)3+x+ 1 x1(d)e x (e) e 0.5t (f) e z/3 (b)e 2x −e −2x1(g)e 4t (h) e −2.5x(c)2sin3x +cos3x( )t(d)sec(2t + π) +cot3 Integratethe following expressions usingTable 13.1:2 − π( )(a) sin4x (b) sin9t( )( )t(e)tan +cosec(3t − π)x 2t2(c) sin (d) sin2 5(e) cos7x (f) cos(−3x)(f) sinx + x 3 + 1 e( )x5t1(g) cos (h) tan9x(g)3cos(3x)( ) 2(i) cosec2x (j) sec5t(h) t + 1 (k) cot8y (l) cos(5t +1)t(m) tan(3x +4) (n) sin(3t − π)1( ) (i)x3e 2x(o) cosec(5z +2) (p) sec2 +1 (j) tan(4t −3) +2sin(−t −1)( )2t(k)1+2cot3x(q) sin3 −1 (r) cot(5 −x)( ) ( )t t(l) sin −3cos(s) cosec(π −2x)2 24 UseTable 13.1 to integrate the following expressions: (m)(t −2) 21 1(n)3e −t −e −t/2(a)1+x 2 (b) √1−x 2(o)7 −7x 6 +e −x1 1(c) √ (d)(p) (k +t) 2 k constant4−x 2 9+z 2 (q)ksint −coskt k constant

Therefore,

∫ 1

sinmtsinnt dt = {cos(m −n)t −cos(m +n)t}dt

2

= 1 { }

sin(m −n)t sin(m +n)t

− +c

2 m −n m +n

13.2 Elementary integration 439

EXERCISES13.2

1 Integratethe following expressions usingTable 13.1:

1 1

(e) √ (f)

(a) x 10 (b) 9 (c) x 1.5

0.25 −x 2 0.01 + v 2

(d) √ 1 1

1

(g)

t (e) (f) −3.2

10 6 +r 2 (h)

10+t 2

z

1 1

1 1

(g)

x 3 (h) √ (i) (x 2 ) 3

(i) √ (j)

t 2−x 2 1

(j) x −2 (k) t 1/3

9 +x2

5 Integratethe followingexpressions:

2 Integratethe following expressions usingTable 13.1:

(a) e 5x (b) e 6x (c) e −3t (a)3+x+ 1 x

1

(d)

e x (e) e 0.5t (f) e z/3 (b)e 2x −e −2x

1

(g)

e 4t (h) e −2.5x

(c)2sin3x +cos3x

( )

t

(d)sec(2t + π) +cot

3 Integratethe following expressions usingTable 13.1:

2 − π

( )

(a) sin4x (b) sin9t

( )

( )

t

(e)tan +cosec(3t − π)

x 2t

2

(c) sin (d) sin

2 5

(e) cos7x (f) cos(−3x)

(f) sinx + x 3 + 1 e

( )

x

5t

1

(g) cos (h) tan9x

(g)

3

cos(3x)

( ) 2

(i) cosec2x (j) sec5t

(h) t + 1 (k) cot8y (l) cos(5t +1)

t

(m) tan(3x +4) (n) sin(3t − π)

1

( ) (i)

x

3e 2x

(o) cosec(5z +2) (p) sec

2 +1 (j) tan(4t −3) +2sin(−t −1)

( )

2t

(k)1+2cot3x

(q) sin

3 −1 (r) cot(5 −x)

( ) ( )

t t

(l) sin −3cos

(s) cosec(π −2x)

2 2

4 UseTable 13.1 to integrate the following expressions: (m)(t −2) 2

1 1

(n)3e −t −e −t/2

(a)

1+x 2 (b) √

1−x 2

(o)7 −7x 6 +e −x

1 1

(c) √ (d)

(p) (k +t) 2 k constant

4−x 2 9+z 2 (q)ksint −coskt k constant

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