Q.

The sum of the areas of the two squares is 468 square metres. If the difference of their perimeters is 24 metres, find the lengths of the sides of the two squares.

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a

12m and 18m

b

10m and 15m

c

12m and 16m

d

10m and 18m

answer is C.

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Detailed Solution

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Let us assume the sides of the two squares are 'a' and 'b', where 'a' is the side length of the first square and 'b' is the side length of the second square.

We know that: Area of square = (Side)2

So, the area of the first square = a2

The area of the second square = b2

According to the question;

a2 + b2 = 468  ...(i)

The perimeter of a square is given by the formula: Perimeter = 4 × Side length

The difference in their perimeters is given as 24 metres. So, we can write the equation as:

4a - 4b = 24

⇒ a - b = 6

⇒ a = b + 6   ...(ii)

Now, substituting the value of 'a' into equation (i), we get;

b+62+b2=468

b2+12b+36+b2=468

2b2+12b-432=0

b2+6b-216=0

b2+18b-12b-216=0

b+18b-12=0

b=12, -18

Since the value of 'b' must be positive.

Therefore, b = 12 m

Now substituting the value of 'b' in equation (ii), we get;

⇒ a = 18 m

So, the sides of the two squares are 18 m and 12 m, respectively.

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