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C. B. Given: AB = CD 1/5 AD = CB Prove: ABCD is a parallelogram hint: congruent triangles, alt interior angles conv. <1. <3. <4. <2. D. A. statement reason AB = CD given AD = CB given
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C B Given: AB = CD 1/5 AD = CB Prove: ABCD is a parallelogram hint: congruent triangles, alt interior angles conv <1 <3 <4 <2 D A statement reason AB = CD given AD = CB given Draw AC through any two points there exists exactly one line
C B Given: AB = CD AD = CB Prove: ABCD is a parallelogram <1 <3 <4 <2 D A statement reason AB = CD given AD = CB given Draw AC through any two points there exists exactly one line AC = AC reflexive property ∆ABC = ∆CDA SSS <1 = <2 CPCTC BC // DA alternate interior angles converse <3 = <4 CPCTC AB // CD alternate interior angles converse ABCD is a parallelogram definition of a parallelogram
C B Given: <B = <D 2/5 <A = <C Prove: ABCD is a parallelogram hint: quad sum thm, consec angle conv D A statement reason <B = <D given <A = <C given
C B Given: <B = <D <A = <C Prove: ABCD is a parallelogram D A statement reason <B = <D given <A = <C given <A +<B +<C + <D = 360 quadrilateral sum theorem <A + <B + <A + <B = 360 substitution 2<A + 2<B = 360 combine like terms 2(<A + <B) = 360 distributive property <A + <B = 180 division property BC // DA consecutive interior angles converse <A + <D + <A + <D = 360 substitution 2<A + 2<D = 360 combine like terms 2(<A + <D) = 360 distributive property <A + <D = 180 division property AB // CD consecutive interior angles converse ABCD is a parallelogram definition of a parallelogram
C B Given: <A + <B = 180 3/5 <A + <D = 180 Prove: ABCD is a parallelogram D A statement reason <A + <B = 180 given <A + <D = 180 given
C B Given: <A + <B = 180 <A + <D = 180 Prove: ABCD is a parallelogram D A statement reason <A + <B = 180 given <A + <D = 180 given BC // DA consecutive interior angles converse AB // CD consecutive interior angles converse ABCD is a parallelogram definition of a parallelogram
C B Given: AE = CE 4/5 BE = DE Prove: BC // DA hint: congruent triangles, alt interior angles conv E D A statement reason AE = CE given BE = DE given
C B Given: AE = CE BE = DE Prove: BC // DA E D A statement reason AE = CE given BE = DE given <BEC = <DEA vertical angle theorem ∆AED = ∆CEB SAS <ADE = <CBE CPCTC BC // DA alternate interior angles converse
C B Given: AE = CE 5/5 BE = DE Prove: ABCD is a parallelogram hint: 2 pairs of congruent triangles, alt interior angles conv E D A statement reason AE = CE given BE = DE given
C B Given: AE = CE BE = DE Prove: ABCD is a parallelogram E D A statement reason AE = CE given BE = DE given <BEC = <DEA vertical angle theorem ∆AED = ∆CEB SAS <ADE = <CBE CPCTC BC // DA alternate interior angles converse <BEA = <DEC vertical angle theorem ∆AEB = ∆CED SAS <ABE = <CDE CPCTC AB // CD alternate interior angles converse ABCD is a parallelogram definition of a parallelogram