Memory Game Plane geometry (D)Online version Basic Questions about Geometry by Tatiana Cruz A triangle has three sides. How many sides does a triangle have? What type of angle measures exactly 180 degrees? A straight angle measures exactly 180 degrees. A square has four right angles. How many sides does a triangle have? A square has four right angles. How many right angles are there in a square? How many right angles are there in a square? How many diagonals does a pentagon have? What type of angle measures exactly 180 degrees? A straight angle measures exactly 180 degrees. How many diagonals does a pentagon have? A triangle has three sides.