Area of Triangle Formula: In general, "area" refers to the region inside the boundary of a flat object or figure and is measured in square units, with the standard unit being square meters (m²).

21 pennies, small blocks or other small stackable objects. More sheets of paper (optional) ... 5 and 3 pennies in the circles lining up on one side of the triangle, for example, ...

The optical illusion of the impossible triangle in Perth, Australia. Seen from the right angle, this sculpture looks like a Penrose triangle. Credit: Bjørn Christian Tørrissen / Wikimedia Commons ...