So you want to know how many degrees are in a quadrilateral? Why didn't you ask?! Oh ... you were wondering why we called it the quadrilateral angle sum? Well, maths is a big fat trick! We love to use language which confuses you. I'm here to make sure that you understand that stupid language.
I open the video by looking at angles in a triangle being 180 degrees and how we can use that to find the number of degrees in any polygon. Using this information we see that the angles in a quadrilateral add to 360 degrees. Using this fact we look at lots of examples which have quadrilaterals including convex and non-convex.
I had so much fun! Hope you enjoyed the video.