Originally Posted by

**aoibha** Could anybody pease explain to me where I have gone wrong in the sum below the answer is ment to be t = 0.5

The line p(t) starting at [2,-1,1] and going in the direction [1,3,-2] and the plane defined by 3x+y -2z = -2

using the formula: t =

-n.s + n.po

_________

n.v

I took s = [2,-1,1] v = [1,3,-2] n = [3,1 -2] and n.p0 = -2

-n.s = [3,-1,2].[2,-1,1] = [-6,1,2] **<--- NO! The result is -3**

n.v = [3,1,-2].[1,3,-2] = [3,3,4] **<--- NO! The result is 10**

[-6,1,2] -2

_________

[3,3,4]

[-8,-1,0]

_______

[3,3,4]

t = [-2.6, -0.3,]

t = [ -2. 9]