Question

Pre-Calculus and Trigonometry: PLEASE HELP AND EXPLAIN!!!

What is the projection of (2, 5) onto (1, 3)?

A. 0.5(1, 3)
B. 1.7(2, 5)
C. 1.7(1, 3)
D. 0.5(1, 3)

Answer 1

any ideas?

Answer 2

I have no idea. @amistre64

Answer 3

no idea is not good, it means that you have not read over your material.

some idea is better, something to work with.

can you even describe what it is looking for?

Answer 4

I actually don't even understand how to find a projection or what it is. ): @amistre64

Answer 5

its like finding the shadow cast on the floor.

Answer 6

So it's like, if I plotted both these points and drew a line.. how long the line is??

Answer 7

you have 2 vectors



u casts a shadow on v, as if a light were directly above it. u is projected onto v .. let me post so i can reuse the drawing

Answer 8

now we know the direction of the projection, it in the same direction is v

but what is its length? we need to use a cos of the angle between the vectors ... and the length of u, why?

Answer 9

cos(a) = x/v

therefore, the length of x is just u cos(a)