#### Question

Find the length of diagonal of a square with side 8 cm .

#### Solution

Suppose ABCD is a square of side 8 cm.

Here, segment AC is a diagonal of square ABCD.

In ∆ABC,

l(AC)^{2} = l(AB)^{2 }+ l(BC)^{2} (Pythagoras theorem)

⇒ l(AC)^{2 }= (8)^{2} + (8)^{2}

⇒ l(AC)^{2 }= 64 + 64 = 128

⇒ l(AC)^{ }= \[\sqrt{128}\] cm

Thus, the length of diagonal of square is \[\sqrt{128}\] cm .

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Solution Find the Length of Diagonal of a Square with Side 8 Cm. Concept: Some Special Parallelograms - Concept of a Square.