Players take it in turns to choose a dot on the grid. The winner is the first to have four dots that can be joined to form a square.
Players take it in turns to choose a dot on the grid. The winner is the first to have four dots that can be joined to form a parallelogram.
Players take it in turns to choose a dot on the grid. The winner is the first to have four dots that can be joined to form a rhombus.
If I tell you two sides of a right-angled triangle, you can easily work out the third. But what if the angle between the two sides is not a right angle?