3D geometry (a bit thoughtful)

61 Views Asked by At

When we are actually finding the eqn of a plane parallel to the x axis or any other axis then why do we make the direction ratio of respective axis to be zero ? I mean for example, you represent for a plane parallel to x axis as by+cz=d where a=0 but why?

1

There are 1 best solutions below

1
On BEST ANSWER

The coefficients $a,b,c$ in the equation of your plane can be interpreted as the direction cosines of the normal vector to the plane.

Direction cosines are a slightly more general version of the idea of "slope" in 2 variables. See http://en.wikipedia.org/wiki/Direction_cosine

By virtue of the normal being perpendicular to the required plane, the corresponding direction coefficient vanishes.