Odpowiedź :
d1- pierwsza przekątna rombu
d2- druga przekątna rombu
P - pole rombu
P=d1*d2/2|*2
2P=d1*d2|÷d1
d2=2P/d1
d2=60mm^2/10mm
d2=6mm
[tex]P = 30 \ mm^{2}\\d_1 = 10 \ mm\\d_2 = ?\\\\P = \frac{d_1\cdot d_2}{2} \ \ |\cdot2\\\\d_1\cdot d_2 = 2P \ \ /:d_1\\\\d_2 = \frac{2P}{d_1} = \frac{2\cdot30 \ mm^{2}}{10 \ mm} = 6 \ mm\\\\Odp.\boxed{ \ d_2 = 6} \ mm[/tex]