An upside-down triangle where the tip is pointing downward symbolizes the female and the feminine side of things. A triangle with the point facing upward is a masculine symbol.
The upside-down triangle sometimes means mother or that the wearer is passive and ruled by the lunar phases. Alternatively, a triangle with the point facing up stands for father, and the sun is the driving force. The beauty of the equilateral triangle when used in jewelry is that the wearer can turn it to suit changing moods on different days. The wearer of a triangle tattoo should be sure of the triangle's intended meaning beforehand.