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Mathematics 11 Online
OpenStudy (anonymous):

lines

OpenStudy (anonymous):

@Valpey @lgbasallote

OpenStudy (valpey):

Definitely not parallel as the signs are orthogonal.

OpenStudy (anonymous):

since the coefficints of t are the component of the vector parallel to line so we have two vectors v1=<3,1,-2> v2=<2,-1,-1>

OpenStudy (anonymous):

now check the ratio of the two vectors if the ratios of the components of the vectors are equal they will be Parallel. \[\Large \frac{3}{2} \ne \frac{1}{-1} \ne \frac{-2}{-1}\] so they are not parallel.

OpenStudy (anonymous):

But how would I show they are intersecting?

OpenStudy (anonymous):

like i understnad why they arent parallel but how about intersection

OpenStudy (anonymous):

okay for this you have to solve the following x=3t+1 y=t+1 z=-2t now for second line use s instead of t x=2s+3 y=-s z=-s-1 set the both x and y components equal 3t+1=2s+3 t+1=-2s solve these for t and s let me know what you get.

OpenStudy (anonymous):

s= 0 t = -1/3

OpenStudy (anonymous):

sorry try again ! i used t instead of s previously solve these two 3t+1=2s+3 t+1=-2s

OpenStudy (anonymous):

arent those the same things?

OpenStudy (valpey):

If they intersect then for some t and s: <1,1,0>+t<3,1,-2>=<3,0,-1>+s<2,-1,-1> Which translates into three equations: 1+3t =3+2s 1+ t = -s 0- 2t =-1-s

OpenStudy (anonymous):

Oh i see. Let me solve for them

OpenStudy (anonymous):

s =-1 t = 0

OpenStudy (anonymous):

i am committing typo mistakes again and again :( here it is in detail okay for this you have to solve the following x=3t+1 y=t+1 z=-2t now for second line use s instead of t x=2s+3 y=-s z=-s-1 set the both x and y components equal 3t+1=2s+3 t+1=-s solving these two equations t=0 s=-1 now set the z components equal and put the value of s and t -2t=s-1 -2(0)=-1-1 \[\Large 0 \ne -2\] so the lines are not intersecting! these are skew lines

OpenStudy (anonymous):

i said they were skew lines and that was wrong

OpenStudy (anonymous):

@mukushla

OpenStudy (valpey):

s =-1 t = 0 is correct. The lines intersect at <3*0+1,0+1,-2*0> =<1,1,0> and <2*(-1)+3,-(-1),-(-1)-1>=<1,1,0>

OpenStudy (valpey):

@sami-21 you wrote -s-1 then you wrote s-1. Another typo, I suppose.

OpenStudy (anonymous):

yes you are correct actually i made another typo z component is -2t=-s-1 -2(0)=-(-1)-1 0=0 so yes they intersects !!!

OpenStudy (anonymous):

Oh i see thanks guys

OpenStudy (valpey):

Your proof should have ended: now set the z components equal and put the value of s and t -2t=-s-1 -2(0)=-(-1)-1=0

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