12.1

5.(u*cos45°,u*sin45°)
7.(w*cos20°,-w*sin20°)
9.(2-3,7-2)=(-1,5)
11.(1-3,-4-5)=(-2,-9)
15.<5*6,5*2>=<30,10>
21.	2*v=<2*2,2*3>=<4,6>
	-w=<-4,-1>
	v+w=<2+4,3+1>=<6,4>
	2*v-w=<4-4,6-1>=<0,5>
41.sqrt(3^2+4^2)=5
unit vector=<3/5,4/5>
47.e=<cos(4pi/7),sin(4pi/7)>

12.2

11.P=(1-3,4+2,3-3)=(-2,6,0)
13. 	a.<2,4,6>=v/2 
	So they are parallel and in the same direction
	b.<-1,-2,3> doesn't have magnitude relationship with V
	So they are not parallel.
	c.<-7,-14,-21>=-7*v/4
	So they are anti-parallel.
	d.<6,10,14>doesn't have magnitude relationship with V
	So they are not parallel.
19.<-16,-22,-6>+<8,4,4>=<-8,-18,-2>
25.4/2=2 2/(-1)=-2 So they are not parallel.
27.6/(-3)=-2 -2/1=-2 8/4=2 So they are not parallel.
31.sqrt((-4)^2+4^2+2^2)=6
unit vector=<-2/3,2/3,1/3>
49.(1)(5+0,5-2,2+1)=(5,3,3)
     (2)(5-0,5+2,2-1)=(5,7,1)
51.	r1(t)=<4*t-1,2-2*t,t+2>
	r2(t)=<2*t,1,t+1>
because (t+2) not equal to (t+1), so they won't intersect.