# Can 3 planes intersect at a single point? [closed]

I know that three planes can intersect having a common straight line as intersection. But I have seen in some references that three planes intersect at single point.The three planes were represented by a triangle. What is equation of a triangle?

• Really? Are you familiar with $\mathbb R^3$? Jan 22 at 5:19
• They can be triangularly shaped. Jan 22 at 5:19
• Two non-parallel planes intersect in a line. If that line is not parallel to the third plane, then it passes through it at a single point.
– Karl
Jan 22 at 5:45
• what about the three coordinate planes?? Jan 22 at 5:47
• The x-y,y-z and z-x plane intersecting at origin. Jan 22 at 5:55

The general equation for a plane is $$ax+by+cz=d$$ for constants $$a,b,c,d.$$

I can't comment on the specific example you saw; you may often see a triangle as a representation of a portion of a plane in a particular octant. But three planes can certainly intersect at a point: consider the three coordinate planes, $$x=0,y=0,z=0$$.

And if you want all possibilities:

• Golden_Ratio. Very nice. Jan 22 at 8:07
• Thanks @PeterSzilas Jan 22 at 8:13