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there is 9 planes of symmetry in a cube
There are 31 planes of existence in Buddhist belief
Two planes intersect at a line. The line where they intersect pertains to both planes. In the same manner, if infinitely many planes intersect each other at the same line, then that line pertains to the infinitely many planes.
it has 5 planes of symmetry
it has 5 planes: the base and 4 sides.