## Practice Set 45

**Important Formula :**

#### Area of a square =(side²)

#### Area of a rectagle = Length X Breadth

**1) Find the area of a square having side 12 cm.**

-> Area of a square =(side²)

= ( 12 X 12)

= 144 cm²

**2) The length of a rectangle is 15cm and breadth is 5 cm. Find its area?**

-> The Area of a rectangle = Length X Breadth

= 15 X 5

= 75 cm²

**3) The area of a rectangle is 102 cm². If its length is 17 cm. What is its perimeter?**

-> (Here, area if rectangle is given as 102 and length as 17 but breadth is not given)

Area of a rectangle = Length X Breadth

∴ 102 = 17 X Breadth

∴ 102 /17 = Breadth

∴ 6 = Breadth

**The perimeter of rectangle**= 2(l + b)

= 2 (17 + 6)

= 2 X 23

= 46 cm

**4) If the side of a square is tripled, how many times will its area be as compared to the area of the original square?**

-> Let the side of the square be x cm

∴ Area of square = x X x

∴ = x²cm

Now, If the side of a square is tripled, then its side will be 3x

∴ Area of new square = 3x X 3x

∴ = 9x² cm

∴ 9x² is 9 times of x²

∴ The area of the new square is 9 times the area of the original square.

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