Xem giải mà vẫn ko làm đc

C

colang20

N

nhokdangyeu01

Gọi S là diện tích hinh bình hành ABCD
a, Ta có
$S_{DAC}$=$\frac{1}{2}$S
$S_{DCK}$=$\frac{2}{3}S_{BCD}$=$\frac{2}{3}$ * $\frac{1}{2}$ S =$\frac{1}{3}$S
\Rightarrow $S_{DAC}$=$\frac{3}{2}S_{DCK}$
b,Ta có
$S_{ADLB}$=S-$S_{DCL}$=S-$\frac{1}{3}S_{BCD}$=S-$\frac{1}{3}$*$\frac{1}{2}$S=$\frac{5}{6}$S
\Rightarrow $S_{ADLB}$=$\frac{5}{3}S_{ADB}$
c,$S_{ABKD}$=S-$S_{CDK}$=S-$\frac{2}{3}S_{BCD}$=S-$\frac{2}{3}$*$\frac{1}{2}$S=$\frac{2}{3}$S
\Rightarrow $S_{ABLD}$=$\frac{5}{4}S_{ABKD}$
 
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