Question

in trapezul abcd ,AB paralel CDEF]este linia mijlocie .daca EF=7cm si AB=9cm.sa se afle CD

Answer 1

EF = $\frac{B+b}{2} = \frac{AB+CD}{2} = \frac{9+CD}{2}$
7 = $\frac{9+CD}{2}$
7·2 = 9 + CD
14 = 9 + CD
CD = 14 - 9
CD = 5 cm