Find the length of a diagonal of a rhombus when the area is 48 and the other diagonal is 12.
Let the rhombus be ABCD with diagonal AC given = 12, and we are
to find the length of diagonal BD:
The diagonals of a rhombus are perpendicular bisectors of each
other. Therefore since AC is given equal to 12, AE = EC = 6.
Since triangle ABD and CBD are congruent, and the entire rhombus
has area 48, each of those triangles has area 24.
Area of triangle ABD =
base×height
24 =
BD·AE
24 =
BD·6
24 = 3·BD
8 = BD
Edwin