Пропорционални отсечки

[Гост]

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[ammornil]

[tex]\frac{AB}{CD}=\frac{A_{1}B_{1}}{C_{1}D_{1}}[/tex]

а) [tex]AB=90cm; CD=18cm; A_{1}B_{1}=60cm, C_{1}D_{1}=?[/tex]
[tex]\frac{AB}{CD}=\frac{A_{1}B_{1}}{C_{1}D_{1}} \Leftrightarrow \frac{90}{18}=\frac{60}{C_{1}D_{1}} \Leftrightarrow 5C_{1}D_{1}=60 \Leftrightarrow C_{1}D_{1}=12cm[/tex]

б) [tex]CD=36cm; A_{1}B_{1}=40cm; C_{1}D_{1}=12cm, AB=?[/tex]
[tex]\frac{AB}{CD}=\frac{A_{1}B_{1}}{C_{1}D_{1}} \Leftrightarrow \frac{AB}{36}=\frac{40}{12} \Leftrightarrow AB=\frac{10.36}{3} \Leftrightarrow AB=120cm[/tex]