
We know in rhombus diagonals bisect each other at right angle.
In ΔAOB
BO = \(\frac{BD}{2}\) = \(\frac{16}{2}\) = 8 cm
Using pythagorous theorem in ΔAOB
AB2 = AO2 + BO2
102 = AO2 + 82
100 - 64 = AO2
AO2 = 36
AO = \(\sqrt{36}\) = 6 cm
Therefore length of diagonal AC of rhombus ABCD is 6 × 2 = 12cm