△BEF的面积|四年级奥数题及答案
如图,在平行四边形ABCD中,直线CF交AB于E,交DA延长线于F,若S△ADE=1,求△BEF的面积.
答案:
nmousewheel="return bbimg(this)" border=0 hspace=0 alt="" href="https://img.peixunla.com/202407/05/091938361.jpg" data-fancybox="images">nmousewheel="return bbimg(this)" border=0 hspace=0 alt="" src="https://img.peixunla.com/202407/05/091938361.jpg" o
nload=resizepic(this)>
连结AC,∵AB//CD,∴S△ADE=S△ACE
又∵AD//BC,∴S△ACF=S△ABF
而 S△ACF=S△ACE+S△AEF∶S△ABF=S△BEF+S△AEF
∴ S△ACE=S△BEF ∴S△BEF=S△ADE=1.