Hey need some help with some questions

1.)Consider the points P = (3,-1,2) , Q=(4,1,-5) , and R=(-1,3,3).

a. Compute the distance from the Origin O=(0,0,0) to the line PQ.

b. Compute the distance from the origin to the plane PQR.

c. Compute the distance between the lines PQ and OR.

I "think" the formula is

$\displaystyle |U x V| / |v|$

so far a.)

PQ= < 1, 2 , -7 >

So if my formula is correct I believePQwould be V. What would be U? <0,0,0> ?

b.)

PQR= <2,-1, -10> ?

for c.)

PQ= <1,2,-7>

OR= <-1,3,3>

Any help in the right direction or if you could list the process would be of great help.