Analytical Geometry help please!
I really hope someone can help with this.
I am afrikaans so please excuse my english names.
We have a project in Maths asking us the following:
In a rectangle ABC, where a line connects C directly with the basis with AB to form a 90 degrees angle(i believe its called a hightline, in direct translation).
They now want us to prove this(Why it forms a 90 degree angle) by using Analytical geomatry, can someone help out 'n bit please?