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I(2n)
=∫(0->π/2) (cosx)^(2n) dx
=∫(0->π/2) (cosx)^(2n-1) dsinx
=[(cosx)^(2n-1) .sinx]|(0->π/2) +(2n-1)∫(0->π/2) (cosx)^(2n-2) .(sinx)^2 dx
=0 +(2n-1)∫(0->π/2) (cosx)^(2n-2) .[1-(cosx)^2] dx
2nI(2n) =(2n-1)∫(0->π/2) (cosx)^(2n-2) dx
=(2n-1)I(2n-2)
I(2n)= [(2n-1)/(2n)].I(2n-2)
∫(0->π/2) (cosx)^2 dx
=I2
=(1/2)I0
=(1/2)∫(0->π/2) dx
=(1/2)(π/2)
=π/4
∫(0->π/2) (cosx)^4 dx
=I4
=(3/4)I2
=(3/4)(1/2)I0
=(3/4)(1/2)(π/2)
=3π/16
=∫(0->π/2) (cosx)^(2n) dx
=∫(0->π/2) (cosx)^(2n-1) dsinx
=[(cosx)^(2n-1) .sinx]|(0->π/2) +(2n-1)∫(0->π/2) (cosx)^(2n-2) .(sinx)^2 dx
=0 +(2n-1)∫(0->π/2) (cosx)^(2n-2) .[1-(cosx)^2] dx
2nI(2n) =(2n-1)∫(0->π/2) (cosx)^(2n-2) dx
=(2n-1)I(2n-2)
I(2n)= [(2n-1)/(2n)].I(2n-2)
∫(0->π/2) (cosx)^2 dx
=I2
=(1/2)I0
=(1/2)∫(0->π/2) dx
=(1/2)(π/2)
=π/4
∫(0->π/2) (cosx)^4 dx
=I4
=(3/4)I2
=(3/4)(1/2)I0
=(3/4)(1/2)(π/2)
=3π/16
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