Question

The vertices of ΔDEF are D(7, 3), E(4, -3), and F(10, -3). Write a paragraph proof to prove that ΔDEF is isosceles.

Answer 1

Distance Formula:

\[d = \sqrt{(x _{2} - x _{1})^{2} + (y _{2} - y _{1})^{2}}\]

Answer 2

An isosceles triangle has two congruent lengths

Answer 3

and itʻs base angles are congruent

Answer 4

Find the distance between each point. If two of the three answers are congruent, thatʻs one set of proof. If we do law of Cosines to figure out all the angles, we can confirm the base angles as well

Answer 5

THANK YOU!!!!!!!!

Answer 6

The formula for Law of Cosines is as follows...

\[a ^{2} = b ^{2} + c ^{2} -2bc (cosA)\]

Answer 7

You got it?

Answer 8

YES (:

Answer 9

Ok, let me know if you need help