Question

what is the projection of (2,5) onto (1,3)?
a. 1.7(2,5)
b. 1.7(1,3)
c. 0.5(1,3)
Please help I don't know what it means by projection

Answer 1

do you know the dot product of the vectors

Answer 2

no

Answer 3

for vectors
a.b = |a||b|cos x where x is the angle between a and b

Answer 4

okay so how do I use that to solve the problem?

Answer 5

suppose we want projection of b on a
then it is given by |b|cosx
which equals (a.b)/|a|

Answer 6

I'm sorry I still don't understand how this applies to my problem? Is (2,5) a and b or is (1,3)?

Answer 7

is your question related to vectors

Answer 8

yes

Answer 9

then a is (2,5) and b is (1,3)

Answer 10

a.b=2.1 +5.3 =17

Answer 11

wait so are you saying (2*5)/ 2 equals either 1.7 or 0.5?

Answer 12

but here we need (a.b) / |b|
here |b| = sqrt(1^2 +3^2)= sqrt(10)

Answer 13

okay i got 5.3

Answer 14

the answer is 1.7(1,3)