Maths

Grade9girl

pls can someone clarify how they got the vectors 3i+4j and 5i for this question? I am just trying to attach it...

(edited 1 year ago)

Reply 1

Grade9girl

Original post by Grade9girl

pls can someone clarify how they got the vectors 3i+4j and 5i for this question? I am just trying to attach it...

btw i got part a right but im not sure which point theyre using to start with for vectors

Reply 2

username5966604

Not gonna be the best explanation but its asking you for the two values of k where the distance from the starting point to the end will be 5. If k was 0.5, then halve the length of the b line and you will see that the vector is 3i + 4j, 3 right 4 up. This gives a length of 5 as 3squared + 4squared = 5squared. Same way that you can extend the b vector line across and notice there's another point at which b is multiplied by 1.5 where the length is also 5. This is just 5i as there's no change in the y vector.

So you can take a compass or something or even just visualise a length of 5 blocks going from the starting point. It will only touch the end part of the vector on those two points