Mathematics - 3D Coordinate Geometry Question with Solution | TestHub

The equation of the XY plane is $z=0$.

Any plane parallel to the XY plane has the equation of the form $z=c$, where $c$ is a constant.

Since the required plane passes through the point $A(7,8,6)$, the z-coordinate of the point must satisfy the equation of the plane.

Substituting $z=6$, we get $c=6$.

Thus, the Cartesian equation of the required plane is $z=6$.

Answer: $z=6$