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Question Number 131275 by Engr_Jidda last updated on 03/Feb/21
Orthogonal and Orthonormal sets  given that  y_n (t)=ϱ^t B_n sin((nπ)/4)t   and y_m (t)=ϱ^t B_m sin((mπ)/4)t  show that ∫_0 ^4 y_n (t)y_m (t)dt  is orthogonal and orthonormal
OrthogonalandOrthonormalsetsgiventhatyn(t)=ϱtBnsinnπ4tandym(t)=ϱtBmsinmπ4tshowthat04yn(t)ym(t)dtisorthogonalandorthonormal
Answered by Ar Brandon last updated on 03/Feb/21
℧=∫_0 ^4 ϱ^(2t) B_m B_n sin(((mπ)/4)t)sin(((nπ)/4)t)dt      =−((B_m B_n )/2)∫_0 ^4 ϱ^(2t) {cos((((m+n)π)/4)t)−cos((((m−n)π)/4)t)}dt      =−((2B_m B_n )/π)∫_0 ^π ϱ^((8u)/π) [cos((m+n)u)−cos((m−n)u)]du      =−((2B_m B_n )/π){[cos((m+n)u)−cos((m−n)u)]ϱ^((8u)/π) ∙(π/8)                     −∫[(m−n)sin((m−n)u)−(m+n)sin((m+n)u)]((πϱ^((8u)/π) )/8)}_0 ^π       =((2B_m B_n )/π)∫[(m−n)sin((m−n)u)−(m+n)sin((m+n)u)]((πϱ^((8u)/π) )/8)du      =((2B_m B_n )/π){[(m−n)sin((m−n)u)−(m+n)sin((m+n)u)]((π^2 ϱ^((8u)/π) )/(64))          −∫{(m−n)^2 cos((m−n)u)−(m+n)^2 cos((m+n)u)}((π^2 ϱ^((8u)/π) )/(64))du}_0 ^π        =0
=04ϱ2tBmBnsin(mπ4t)sin(nπ4t)dt=BmBn204ϱ2t{cos((m+n)π4t)cos((mn)π4t)}dt=2BmBnπ0πϱ8uπ[cos((m+n)u)cos((mn)u)]du=2BmBnπ{[cos((m+n)u)cos((mn)u)]ϱ8uππ8[(mn)sin((mn)u)(m+n)sin((m+n)u)]πϱ8uπ8}0π=2BmBnπ[(mn)sin((mn)u)(m+n)sin((m+n)u)]πϱ8uπ8du=2BmBnπ{[(mn)sin((mn)u)(m+n)sin((m+n)u)]π2ϱ8uπ64{(mn)2cos((mn)u)(m+n)2cos((m+n)u)}π2ϱ8uπ64du}0π=0
Commented by Engr_Jidda last updated on 03/Feb/21
Thank you so much sir.  is this for orthogonal or orthonormal?
Thankyousomuchsir.isthisfororthogonalororthonormal?
Commented by Ar Brandon last updated on 03/Feb/21
��I don't really know Sir. I'm a student. I just solved the calculus and left the conclusion to be made by you. Assuming you have studied the topic��
Commented by Engr_Jidda last updated on 03/Feb/21
yes sir, thank you once again
yessir,thankyouonceagain