# How do you show that the triangle with verticies D ( -2,5), E (- 4,1), F (2,3) is a right angle triangle?

##### 1 Answer

Dec 7, 2015

#### Answer:

Prove right triangle

#### Explanation:

We prove that line DE is perpendicular to DF by showing that the product oftheir slopes is (-1).

Slope of line ED:

(yD - yE)/(xD - xE) = (5 - 1 )/(-2 + 4) = 4/2 = 2

Slope of EF:

(yF - yD)/(xF - xD) = (3 - 5)/(2 + 2) = -2/4 = -1/2.

The product of the 2 slopes is (-1), therefor, the triangle DEF is a right triangle.