(1.) ∫sin3
x cos2 x dx here is
the problem
= ∫(cos2
x)(1 - cos2 x)(sin x)dx
factor like this
= ∫cos2
x sin x dx - ∫cos4 x sin x dx
multiply thru
= (-1/3)cos3 x + (1/5)cos5
x + C integrate
(2.) ∫ sin3
x sec x dx here is the
problem
= ∫ tan x
sec2 x dx use
this trig id
= (1/2)tan2 x + C integrate
(3.) ∫ cos3
x sin1/2 x dx here
is the problem
= ∫(1 - sin2
x)(cos x)(sin1/2 x)dx
factor
= ∫sin1/2
x cos x dx - ∫sin5/2 x cos x dx
multiply thru
= (2/3)sin3/2 x - (2/7)sin7/2
x + C integrate
(4.) ∫ cos3
x csc1/2 x dx here
is the problem
= ∫ cos3
x sin-1/2 x dx
reciprocal identity
= ∫(1 - sin2
x)(cos x)(sin-1/2 x)dx trig
id, factor
= ∫sin-1/2
x cos x - ∫sin3/2
x cos x dx multiply thru
= 2 sin1/2 x - (2/5)sin5/2
x + C integrate
(5.) ∫ sin5
x cos2 x dx here is
the problem
= ∫(1 - cos2
x)2 * (cos2 x)(sin x) dx trig id, factor
= ∫(1 - 2 cos2 x + cos4 x)(cos2
x)(sin x)dx square the binomial
= ∫cos2
x sin x dx - 2∫cos4 x sin x + ∫cos6
x sin x dx
[multiply thru parentheses]
= (-1/3)cos3 x + (2/5)cos5
x - (1/7)cos7 x + C integrate
(6.) ∫ sin5
x sec2 x dx here is
the problem
= ∫(sin5
x)(cos-2 x)dx
reciprocal identity
= ∫(1 - cos2
x)2(sin x)(cos-2 x)dx
trig id
= ∫(1 - 2cos2
x + cos4 x)(sin x)(cos-2 x)dx
[square the binomial]
= ∫cos-2
x sin x dx - 2∫sin x dx + ∫cos2
x sin x dx
[multiply thru parentheses]
= -(cos x)-1 + 2 cos x -
(1/3)cos3 x + C integrate
= - sec x + 2 cos x - (1/3)cos3
x + C reciprocal id
(7.) ∫ sin2
x cos5 x dx here is
the problem
= ∫(sin2
x)(1 - sin2 x)2(cos x)dx factor, trig id
= ∫(sin2
x)(1 - 2sin2 x + sin4 x)(cos x)dx
[square the binomial]
= ∫sin2
x cos x dx - 2∫sin4 x cos x dx + ∫sin6
x cos x dx
[multiply thru parentheses]
= (1/3)sin3 x - (2/5)sin5
x + (1/7)sin7 x + C
integrate
(8.) ∫ sin2
x tan x dx here is the problem
= ∫ sin3
x sec x dx trig id
= ∫(1 - cos2
x)(sin x)(cos x)-1 dx trig
id's
= ∫(cos x)-1
sin x dx - ∫cos x sin x dx multiply
thru
= - ln cos x - (1/2)sin2 x +
C integrate
(9.) ∫ cos2
x dx here is the problem
= (1/2)∫(1 + cos
2x)dx half angle id for cos
= (1/2)∫ dx +
(1/2)∫cos 2x dx multiply
thru parentheses
= (1/2)x + (1/4)sin 2x + C integrate
(10.) ∫ sin4
x dx here is the problem
= (1/4)∫(1 - cos
2x)2 dx half angle id for
sine
= (1/4)∫(1 - 2
cos 2x + cos2 2x) dx square
the binomial
= (1/4)∫dx -
(1/2)∫cos 2x dx + (1/4)(1/2)∫(1 + cos
4x)dx
[multiply thru parentheses][half angle id for cos]
= (1/4)∫dx -
(1/2)∫cos 2x dx + (1/8)∫dx +
(1/8)∫cos 4x dx
[multiply thru parentheses]
= (1/4)x - (1/2)(1/2)sin 2x + (1/8)x +
(1/8)(1/4)sin 4x + C
= (3/8)x - (1/4)sin 2x + (1/32)sin 4x +
C multiply
[and combine like terms]