The area of a rhombus with side 13 cm and one diagonal 10 cm will be :

Answer: Option C

Side of a rhombus = 13 cm
Diagonal of rhombus = 10 cm
In ΔAOB
$$\begin{array}{rl}& AO=\sqrt{{13}^2-5^2}\\ & =\sqrt{169-25}\\ & =\sqrt{144}\\ & =12cm\end{array}$$
$$\begin{array}{rl}& \Rightarrow AC=24\\ & \text{Area of rhombus :}\\ & =\frac{1}{2}\times d_1\times d_2\\ & =\frac{1}{2}\times 24\times 10\\ & =120sq.cm\end{array}$$