Prove: The opposite sides of a parallelogram are equal.

Question

Prove: The opposite sides of a parallelogram are equal.

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i completed some of it but i am so confused

Answer 1

A=(0,0), B=(b,0), C=(b+c,d), D=(c,d)

use the distance formula

DC=√(c-[b+c])²+(d-d)²

DC=√b²

DC=b

AB=√(0-b)²+(0-0)²

AB=√(-b)²

AB=√b²

AB=b

therefore DC=AB

 

DA=√(c-0)²+(d-0)²

DA=√c²+d²

CB=√(b+c-b)²+(d-0)²

CB=√c²+d²

therefore DA=CB