A football field is situated such that when you look from one goal post to the other you are facing directly northwest. A receiver catches a pass 40.0 yards from the northwest goal line. The receiver runs 10.0 yds northwest, 10.0 yds west, and then 15.0 yds north. How far from the goal line is the receiver after his run?

Question

fifciol · Answer

|dw:1377960063280:dw|
Add vectors:
d, our goal = [x,y]
$$[x,y]=[40\cos45^o,40\sin45^o]+[10\cos45^o,10\sin45^o]+[10,0]+[0,15]$$
Then pythagoras to find magnitude of that distance

anonymous · Answer

@Fifciol the cosine should be 135 degrees thus it is negative, right?

fifciol · Answer

It doesn't matter which direction for increasing values you choose cause we're only interested about magnitude

anonymous · Answer

@Fifciol the resultant vector I get is larger than 40 yd.

fifciol · Answer

yes

anonymous · Answer

@Fifciol  I think I get it, thanks a lot!

fifciol · Answer

yw:)