Could someone please explain to me why the formula that is being used is being used in part c particularly (as in explaining the formula)?
To be clear, I am talking about the (r - r_0) * [(r_1 - r_0) x (r_2 - r_0)] = 0 formula. If you're unsure of what I am asking or need more information or something, just ask.
Sorry if this is not the right place to post but I don't know where else to post it since it's in my calculus course.
Any input would be appreciated!
Thanks in advance!