Question

如图在三角形abc中,ad是一条角平分线,de平行ac,交ab 于点e,de=3,be=4,则ab等于多少

Answer 1

∵AD平分∠BAC,

∴∠DAE=∠DAC,

∵DE∥AC,∴∠AD=∠DAC,

∴∠ADE=∠DAE,

∴AE=DE=3,

∴AB=AE+BE=7.