Answer:
15 cm
Step-by-step explanation:
You need to remember 2 theorems about a rhombus.
1. The diagonals of a rhombus bisect each other
2. The diagonals of a rhombus are perpendicular to each other
In other words, the diagonals of a rhombus are perpendicular bisectors.
BE = 9 and AE = 12
ΔAEB is a right triangle. So, the Pythagorean theorem says
[tex]9^{2} + 12^{2} = AB^{2}[/tex]
[tex]AB^{2}[/tex] = 81 + 144
= 225
AB = [tex]\sqrt{225} = 15[/tex] cm
