Question

Using coordinate geometry to prove that the diagonals of a square are perpendicular to each other.
Given: Vertices are at A(0,0), B(a,0), C(a,a) and D(0,a) Slope of AC=1; Slope of BD=-1

type your proof.
(I've gotten help on this earlier but I still don't understand. Mathmate said"The product of the slopes of two lines intersecting at right angles is -1. You can take it from here."

Answer 1

Mathmate is correct. This is a one-step proof. They already tell you what the slopes are. The product is -1, so they are perpendicular.

For a proof of that theorem, see
http://whyslopes.com/Analytic-Geometry-Functions/analGeo09b_Perpendicular_Lines.html

Answer 2

ok thank you very much the website helped ALOTT :)

Answer 3

use phagoras theorm to find the length of each of the following

Answer 4

true or false: if their sum is equal to 180 degrees, then angle D and angle B are supplementary