which of these is a triangle?
First, we have to remember what a triangle is. A triangle is a three-sided flat shape. Which of these three shapes have three sides? The yellow shape has no sides. It cannot be a triangle. The blue shape has four sides: one, two, three, four. The blue shape cannot be a triangle. What about the green shape? How many sides does it have? One, two, three. The green shape is a triangle.