Originally Posted by

**antikv** please help turn this vector equation [x,y,z]=[3,7,-5]+s[1,2,-1]+t[1,-2,3] into a scalar equation

in the form of x+y+z+D=0

i understand in the case of [x,y]=[3,7,-5]+s[1,2,-1]

the direction vector is [1,2,-1] and the normal vector is [3,7,-5]

all i need to do in this case was to do

as the following

[x-1](3)+[y-2](7)+[z+5](-5)

which would give me the scalar equation 3x+7y-5z-42=0

but how would you find the scalar equation if you have 2 direction vectors?

i have a quiz tommorwT_T but still dont get this question... OTL

hugs and kisses to anyone who can help/solve it for me....thanks in advance