Question

Va rog ajutor urgent!! Multumesc!

Answer 1

$Segmentele~A_{1}A_{2}~si~A_{2}A_{3}~sunt~proportionale~cu~B_{1}B_{2}~si~B_{2}B_{3}$
$\frac{A_{1}A_{2}}{B_{1}B_{2}}=\frac{A_{2}A_{3}}{B_{2}B_{3}}$
$\frac{A_{1}A_{2}}{A_{2}A_{3}}=\frac{B_{1}B_{2}}{B_{2}B_{3}}$
$\frac{21~cm}{B_{2}B_{3}}=\frac{2}{5}$
$21\cdot5=2\cdot B_{2}B_{3}$
$2\cdot B_{2}B_{3}=105$
$B_{2}B_{3}=52,5~cm$