Sum of the areas of two squares is 468 m2. If the difference of their perimeters is 24 m, find the sides of the two squares.
Answers
AnswEr:
- The sides of the squares are 12 m and 18 m.
Given Information:
- Sum of the areas of two squares is 468 m².
- The difference of their perimeters is 24 m.
Need To Find:
- The sides of the two squares = ?
ExPlanation:
Let the sides of the two squares be x m and y m.
Therefore:
- Their perimeter will be 4x and 4y respectively.
- And area of the squares will be x² and y² respectively.
Now Given Here,
4x - 4y = 24
➠ x - y = 6
➠ x = y + 6
Also, x² + y² = 468
➠ (6 + y²) + y² = 468
➠ 36 + y² + 12y + y² = 468
➠ 2y² + 12y + 432 = 0
➠ y² + 6y - 216 = 0
➠ y² + 18y - 12y - 216 = 0
➠ y(y +18) - 12(y + 18) = 0
➠ (y + 18)(y - 12) = 0
➠ y = -18, 12
As we know, the side of a square cannot be negative.
Hence:
- The sides of the squares are 12 m and (12 + 6) m = 18 m.
Sum of the areas of two squares is 468 m²
∵ x² + y² = 468 . ………..(1) .[ ∵ area of square = side²] → The difference of their perimeters is 24 m.
∵ 4x – 4y = 24 [ ∵ Perimeter of square = 4 × side] ⇒ 4( x – y ) = 24
⇒ x – y = 24/4 .
⇒ x – y = 6 .
∴ y = x – 6 ……….(2)
From equation (1) and (2),
∵ x² + ( x – 6 )² = 468
⇒ x² + x² – 12x + 36 = 468
⇒ 2x² – 12x + 36 – 468 = 0
⇒ 2x² – 12x – 432 = 0
⇒ 2( x² – 6x – 216 ) = 0
⇒ x² – 6x – 216 = 0
⇒ x² – 18x + 12x – 216 = 0
⇒ x( x – 18 ) + 12( x – 18 ) = 0
⇒ ( x + 12 ) ( x – 18 ) = 0
⇒ x + 12 = 0 and x – 18 = 0
⇒ x = – 12m [ rejected ] and x = 18m
∴ x = 18 m
Put the value of ‘x’ in equation (2),
∵ y = x – 6
⇒ y = 18 – 6
∴ y = 12 m