Respuestas

  • Usuario de Brainly
2013-04-02T04:55:29+02:00

•.............•...............•.................•

A...........B..............C...............D

 

AB = BD

AC - CD = 28

entonces

(AB+BC) - CD = 28..............BD = BC + CD

(AB+BC) - 28 = CD..............BD - BC  = CD

 

AB + BC - 28 = BD - BC

AB - 28 - BD = - BC - BC

AB - 28 - AB = - 2BC

-28 = - 2BC

-28/-2 = BC

14 = BC

 

espero que te sirva, salu2!!!!