Proofs

Vichien Lindsey

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Joined
Aug 25, 2005
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Prove: if an isosceles triangle has an altitude from the vertex to the base, then the altitude bisects the vertex angle.
Given: angle ABC is isosceles; line CD is the altitude to base line AB
To Prove: line CD bisects angle C

Plan: _______?

Proof:
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Statements / Reasons


the triangle looks kinda like this c

Please help if u can, thanks

a---d---b [/img]
 
Does this do it?
Code:
       C
      /|\
     / | \
    A__D__B
AC = BC
AC²= CD²+AD²
AC²-CD²=AD²
BC²-CD²=BD²=AC²-CD²
AD²=BD²
AD=BD
Congruant triangles by SSS.
I hope the reasons are obvious and legit.
 
I'd suggest renting Euclid's Elements, if you are doing a section on proofs. He is like — Proofs incarnate. I would use him as an example.
 
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