Question

1.如图,三角形ABC中,AB=AC,若将三角形ABC沿着CA方向平移CA长的距离得三角形EFA.

Answer 1

1、∵BC=AF,且BC∥AF

∴ABAF是平行四边形,

∴S△AFB=S△ABC=3

∵△ABC≌△AEF

∴S△AEF=S△ABC=3

∴S四边形BCEF=S△AFB+S△AEF+S△ABC=3+3+3=12

2、原式

=x²-2x+1+x²-9+x²-4x+3

=3x²-6x-5

=3(x²-2x)-5

=3×2-5

=1