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2007-10-05 07:05:32 · 4 answers · asked by smooches 1 in Science & Mathematics Mathematics

4 answers

1-(sinx)^2 =(cosx)^2

so the integral is (cosx)^2 sinx dx

if you write cosx=u then sinx dx =-du

and the integral -u^2 du

which is -u^3/3 so the result is (-1/3) (cosx)^3 +C

2007-10-05 07:13:21 · answer #1 · answered by maussy 7 · 2 2

Integral of sinx(1-(sinx)^2) is found by using the substitution method.
Sinx(1-(sinx)^2) is simplified to sinx((cosx)^2)
by the identity (sinx)^2 + (cosx)^2 =1 , whereby 1 - (sinx)^2 = (cosx)^2
Now the integral becomes (cosx)^2 * sinx
Substituting cosx = t, we have sinx* dx = dt
Now the integral becomes (t^2) dt which is equal to t^3/3
Hence the complete integral is ((cosx)^3) / 3 + C

2007-10-05 07:26:34 · answer #2 · answered by vijay k 1 · 0 2

Notice that (1-(sin x)^2) = (cos x)^2 (Pythagorean identity)

So: int[(sin x)(1-(sin x)^2)] = INT [ sin x * (cos x)^2]

let u=cos x --> du = -sin x dx

= INT -[u^2]dx = -(1/3) u^3 + C === -(1/3) (cos x)^3 + C

2007-10-05 07:20:17 · answer #3 · answered by christian 2 · 0 0

sin(x)(cos²x)=
-1/3cos^3(x)

2007-10-05 07:14:12 · answer #4 · answered by chasrmck 6 · 0 1

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