How do you find a vector of length 10 that is oppositely directed to u=3i-4j?

1 Answer
Shwetank Mauria
Jul 14, 2016

A vector of length 10 that is oppositely directed to u=3i-4j is -6i+8j

Explanation:

A vector oppositely directed to u=3i-4j is v=-u=-(3i-4j) i.e. v=-3i+4j.

However, its length is given by |v|=sqrt((-3)^2+4^2)=sqrt(9+16)=sqrt25=5

What we desire is a vector of length 10 that is double of v and hence

A vector of length 10 that is oppositely directed to u=3i-4j is 2v=2*(-3i+4j)=-6i+8j

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