posted by jenna .
given v=5i+3j and w=-4i+8j, find projwv
There are two kinds of projection of w on to v or of v on to w.
You did not say projection of which on the other or if you want scalar or vector projection.
One important use of dot products is in projections. The scalar projection of b onto a is the length of the segment AB shown in the figure below. The vector projection of b onto a is the vector with this length that begins at the point A points in the same direction (or opposite direction if the scalar projection is negative) as a.
Thus, mathematically, the scalar projection of b onto a is |b|cos(theta) (where theta is the angle between a and b) which from (*) is given by
This quantity is also called the component of b in the a direction (hence the notation comp). And, the vector projection is merely the unit vector a/|a| times the scalar projection of b onto a:
Thus, the scalar projection of b onto a is the magnitude of the vector projection of b onto a.
it was proj with w as a subscript of proj and then v
I am sorry. I am not familiar with that notation. Follow the recipe in the link I gave you.