Question

A diagonal of a rhombus is 20 cm long. If its one side is 26 cm long, find the length of its other diagonal.

Answer 1

If the length of diagonals of rhombus be a and b. Then, length of side is:
$l^2=\frac{1}{4}(a^2+b^2)$
${26}^2=\frac{1}{4}({20}^2+b^2)$
$676=\frac{1}{4}(400+b^2)$
$2704=400+b^2$
$b=48cm$
Hence, length of other diagonal is 48 cm.