Question

Given: triangle ABC is congruent to triangle DEF
a. What is the value of x? Answer

b. What is the length of BC?

Answer 1

Sides BC and EF are corresponding sides of congruent triangles.

They are congrent.

Answer 2

BC = EF

40 - .5x = 9y

Well, that is one equation with two unknowns so we need to look for another relationship in the diagram that has x in it.

Answer 3

Would that be 3x+12 =90?

Answer 4

Look at angles E and B.

Yes, they are congruent so solve 3x+12 =90 for x.

Answer 5

Post what you get for x.

Answer 6

Okidoke so i got x to be 26!

Answer 7

Then, substitute that value of x in for BC's formula.

40 - .5x =

Answer 8

that would be a positive 0.5 right, or would it be negative?

Answer 9

because then its either -13 or just 13

Answer 10

This is BC, right?

40 - .5x =

So find half of x and subtract it from 40 and let's see what we get.

Answer 11

-13 cannot be the side of a triangle. Distances in Geometry are positive.

Answer 12

yeah its BC, annnd i got 27 for the end product of that equation

Answer 13

And gotcha ! I forgot about that

Answer 14

If you are using an algebra calculator, always check the answers. Crazy things pop up sometimes.

Answer 15

Lol yeah i hear yah! and I will!

Answer 16

Okidoke thanks again !! :)

Answer 17

You are welcome.