Hello students in this question we have given that dale e divided by telex. It is equal to minus, They'll be divided by delta T. It is applies to harmonic vector. So the vector, it is equal to the note. Of course K x minus omega t. And be vector. It is equal to be not vector cost of K x minus omega T. So which eaves that he not calls to C b, not? We have to show it. Okay, so hence we can write that this situation from here. So differential differentiating the situation with respect to this X. So we will obtain that minus E note signed of K x minus omega T. And molecular by this case. Okay. And this will be equals two differentiating this. Be vector with respect to this time. So we will often from here that this minus sign. Okay, and due to discuss the differential differentiation will be minus of sign, be not and omega and then K X A sign of Oh, so this differentiation will be equal to be not manipulated by omega sign of K x minus omega t. Okay, so from here, after rearranging, we get from here, this signed K X minus omega T. And this annex this will be cancelled out. So from here we get minus C. Note, it is equal to from here we get the not particularly omega. So now taking the magnitudes only another minus omega will also be there, so minus omega will be there, so this will be cancelled out. So we get from here is not, this is equal to see more clearly. Uh this cave will be there. Okay, so this can be written as omega K. Molecular Beano and this omega bike, it is the speed of the wave and here it is, the speed of the wave that is C and B. Not. So this become the proof for this problem. Thank you.