Find the vector equation of the plane passing through point A(a, 0, 0), B(0, b, 0) and C(0, 0, c). Reduce it to normal form. If plane ABC is at a distance p from the origin, prove that
.

The required plane passes through the point A(a,0,0) whose position vector is
and is normal to the vector
given by
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Clearly,
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The vector equation of the required plane is,
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or, ![]()
or, ![]()
or,
…… (i)
Now, ![]()
For reducing (i) to normal form, we need to divide both sides of (i) by ![]()
Then, we get,
, which is the normal form of plane (i)
So, the distance of the plane (i) from the origin is,
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Hence, Proved.