Angles are measured in degrees, written as °. The maximum angle is 360°. It is the angle all the way round a point. Half of this is the angle on a straight line which is 180°.

You need to prove first that the sum of angles in a triangle is 180 degrees. We know that three sides/angles together add up to 180 degrees, because these together is just the angle around a straight line. So the three angles in the triangle add up to 180 degrees.

Similarly a quadrilateral is a shape with 4 sides. As we know the sum of the angles in a triangle, we can work out the sum of angles in a quadrilateral. We can draw a diagonal line to divide it into two

triangles. Each triangle now will have an angle sum of 180 degrees. Therefore the total angle sum of the quadrilateral will be 360 degrees.

You need to prove first that the sum of angles in a triangle is 180 degrees. We know that three sides/angles together add up to 180 degrees, because these together is just the angle around a straight line. So the three angles in the triangle add up to 180 degrees.

Similarly a quadrilateral is a shape with 4 sides. As we know the sum of the angles in a triangle, we can work out the sum of angles in a quadrilateral. We can draw a diagonal line to divide it into two

triangles. Each triangle now will have an angle sum of 180 degrees. Therefore the total angle sum of the quadrilateral will be 360 degrees.