parametric eqns: line through (1,1,1) parallel to z-axis

[mindy88]

I need help with this problem

The line through (1,1,1) parallel to the z-axis

The answer is X=1, y=1, Z=1+t

What point would I use for the z-axis?

Thanks

 

[pka]

Re: parametric equations

The line through (1,1,1) parallel to the z-axis. The answer is X=1, y=1, Z=1+t .
What point would I use for the z-axis?

What do you mean by that question?
Do you understand how the answer was gotten?
To be parallel to the z-axis the line has direction vector <0,0,1>.

So the equation is: <1,1,1>+t<0,0,1>=<1,1,1+t>.

 

[mindy88]

I did use (0,0,1)

but i got

(0-1)i+(0-1)j+(1-1)k=0
which is -i-j=0

then because it's (1,1,1)

i forgot to mention it was to find the parametric equations

so,
x=1-t
y=1-t
z=1


we didn't learn how to do it using your way.

 

[pka]

to find the parametric equations
x=1-t
y=1-t
z=1

Sorry to say but you have been grossly misinformed!
The correct equation for that line is: \(\displaystyle l = \left\{ {\begin{array}{l}
{x = 1} \\
{y = 1} \\
{z = 1 + t} \\
\end{array}} \right.\)

 

[mindy88]

i see, thanks for the help