Four horses are tethered at four corners of a square plot of side 63 metres so that they just cannot reach one another. The area left ungrazed is:  Choices: A) 675.5 m 2 B) 780.6 m 2 C) 785.8 m 2 D) 850.5 m 2 E) 950.5 m 2

Rationale: required area = ( 63 * 63 – 4 * 1 / 4 * 22 / 7 * 63 / 2 * 63 / 2 ) = 850.5 m 2 answer : d
Answer: D