# Thread: Proving a parallelogram is a rhombus help, please. So very confused! D:

1. ## Proving a parallelogram is a rhombus help, please. So very confused! D:

My class is 'learning' about proofs and whatnot, but I can't wrap my head around the problem my teacher assigned us for homework.

Given: Rhombus ABCD
Prove: ACE is isosceles

I know it's isosceles. I mean, it's just one of those things you look at and know. I can't say that, though, and I have no clue where to start or how to go about proving something that seems so obvious to me.

EDIT: Yo entiendo. 8D

2. Staring at the paper did me good.
I understand it now.
The meaning is life is just out of reach; nothing will stop me!
-cackle-

@______@;;

3. For a rhombus, the two diagonals of a rhombus bisect each other (i.e. $\displaystyle AF = FC$) and the intersection of the two diagonals form a right triangle, i.e. $\displaystyle \angle EFC = \angle EFA = 90^{\circ}$.

Now, look at triangles $\displaystyle AFE$ and $\displaystyle CFE$. If you prove that the two right triangles are congruent, then you prove their hypotenuses are congruent and thus, ACE is isoceles. See if you apply the above.