I am helping someone with their National 5 Maths (in Scotland) and we are struggling with the question shown in the image. I also have a copy of the marking scheme and the answer they are looking for seems to be:
calculate the magnitude of V1, which they give as 5 (which is obviously the square root of 16 + 1 + 8), the squares of the coefficients of i, j and k
calculate the magnitude of V2, which they give as 10a (similarly)
and then it's just equating V1 and 2V2
but my question is WHY is the magnitude of V1 = 5? Doesn't it depend on the magnitudes of i, j and k? Am I being daft? There is no further information given about the vectors i, j and k - I even looked back at the previous question to see if it was a follow-on.
Please help!
Thanks.
calculate the magnitude of V1, which they give as 5 (which is obviously the square root of 16 + 1 + 8), the squares of the coefficients of i, j and k
calculate the magnitude of V2, which they give as 10a (similarly)
and then it's just equating V1 and 2V2
but my question is WHY is the magnitude of V1 = 5? Doesn't it depend on the magnitudes of i, j and k? Am I being daft? There is no further information given about the vectors i, j and k - I even looked back at the previous question to see if it was a follow-on.
Please help!
Thanks.