Find the area and perimeter of a square whose length of diagonals is 20\(\sqrt2\) cm....

MATHEMATICS
JAMB 2023

Find the area and perimeter of a square whose length of diagonals is 20\(\sqrt2\) cm.

  • A. 800 cm\(^2\), 80 cm
  • B. 400 cm, 80 cm\(^2\)
  • C. 80 cm, 800 cm\(^2\)
  • D. 400 cm\(^2\), 80 cm

Correct Answer: D. 400 cm\(^2\), 80 cm

Explanation

perimeter of a square

Using Pythagoras theorem

⇒ \((20\sqrt2)2 = x^2 + x^2\)

⇒ 800 = \(2x^2\)

⇒ 400 = \(x^2\)

⇒ x = \(\sqrt400\) = 20 cm

∴ Area of a square = \(x^2 = 20^2 = 400 cm^2\)

∴ Perimeter of a square = 4x = 4 x 20 = 80 cm



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