Thread: Find distance from given point to xy-plane?

so this is my first hw assignment for my multivariable calculus class and i can't seem to figure out how to find the distance from the point (3,7,-5) to the xy-plane. would it just be the distance perpendicularly between the point and the plane, or is there a formula that i have to use?

Originally Posted by damnireekrad

so this is my first hw assignment for my multivariable calculus class and i can't seem to figure out how to find the distance from the point (3,7,-5) to the xy-plane. would it just be the distance perpendicularly between the point and the plane, <--- yes
or is there a formula that i have to use? <--- that depends

Distances between a plane and a point are measured perpendicularly. That means in your case the distance in question is nothing but the absolute value of the z-coordinate.

If the plane is not parallel to the coordinate planes you have to use a formula or you calculate the minimum of all possible distances, using calculus.

Long before you learn Calculus or even general concepts of Cartesian coordinates, you should have learned what "coordinates" mean. In the xy-plane, x is the distance from the point (x,y) to the y-axis and y is the distance to the x-axis. In three dimensions, x is the distance from the point (x, y, z) to the yz-plane, y is the distance to the xz-plane, and z is the distance to the xy-plane.

ahh alright, thank you for clarifying!