1.Segment RA=segment RB, RS||A Substitution
2.∠A = ∠B Given
3.∠A = ∠2Base ∠'s of isosceles triangle =
4.∠B = ∠1If lines ||, alternate interior ∠'s =
5.∠1 = ∠2If lines ||, corresponding ∠'s =
