Cobor perpendicularele AE si BF (E,F∈CD).
EF=AB=6cm.
[tex]DE=CF= \frac{CD-EF}{2} = \frac{12-6}{2}= \frac{6}{2}=3(cm). [/tex]
DF=DE+EF=3+6=9 (cm).
Aplic teorema inaltimii in ΔBDC-dreptunghic in B:
[tex]BF= \sqrt{DF*CF}= \sqrt{9*3}= 3\sqrt{3}(cm). [/tex]
Inaltimea are lungimea de [tex]3 \sqrt{3} [/tex]cm.
