In triunghiul ABC consideram punctul D apartine lui AB si construim DE II BC si E apartine lui AC .
a) Daca AD=3 cm , AB = 9 cm AE=6cm aflati AC
b) Daca DB=12cm , AB=16cm AE-5cm aflati EC
c) Daca AB=12 cm AC=18 cm si AE=3cm aflati AD

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2014-09-01T16:23:35+03:00
A) conform teoremei lui Thales  \frac{AD}{DB} = \frac{AE}{EC}
=>  \frac{3}{6} =  \frac{6}{AC-6}
AC-6= \frac{36}{3}
AC-6=12 => AC=19
b) conform teoremei lui Thales
 \frac{4}{12} =  \frac{5}{EC}
=> EC= \frac{60}{4} => EC=15