http://www.ck12.org Chapter 8. Right Triangle Trigonometry
21.A( 3 ,− 5 ),B(− 5 ,− 8 ),C(− 2 , 7 )
22.A( 5 , 3 ),B( 2 ,− 7 ),C(− 1 , 5 )
23.WritingExplain the two different ways you can show that a triangle in the coordinate plane is a right triangle.