I don’t know which one you need help with so I’ll answer #1. A triangle cannot have two right angles because the angles in a triangle have to add up to 180°. Since a right angle is 90°, two of those will make 180°. Since a triangle has three angles, that doesn’t leave anything for the third angle, and you can’t have a 0° angle. Also, you could have figured this out by trying to draw it, it’s impossible! This is because it would require a fourth line to complete the shape, which makes it a square!