The area of a rhombus is 480 cm2, and one of its diagonals measures 48 cm.

Question:

The area of a rhombus is 480 cm2, and one of its diagonals measures 48 cm.

Find 

(i) the length of the other diagonal,

(ii) the length of each of its sides, and

(iii) its perimeter.

 

Solution:

i) Area of a rhombus $=\frac{1}{2} \times d_{1} \times d_{2}$, where $d_{1}$ and $d_{2}$ are the lengths of the diagonals.

$\Rightarrow 480=\frac{1}{2} \times 48 \times d_{2}$

$\Rightarrow d_{2}=\frac{480 \times 2}{48}$

$\Rightarrow d_{2}=20 \mathrm{~cm}$

∴ Length of the other diagonal = 20 cm

(ii) Side $=\frac{1}{2} \sqrt{d_{1}^{2}+d_{2}^{2}}$

$=\frac{1}{2} \sqrt{48^{2}+20^{2}}$

$=\frac{1}{2} \sqrt{2304+400}$

$=\frac{1}{2} \sqrt{2704}$

$=\frac{1}{2} \times 52$

 

$=26 \mathrm{~cm}$

∴ Length of the side of the rhombus = 26 cm

(iii) Perimeter of the rhombus $=4 \times$ Side

$=4 \times 26$

$=104 \mathrm{~cm}$

 

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