Question

What is the area of circle whose radius is diagonal of a square whose area is 4?

Answer 1

area of square = 4 sq. units
⇒ a² =4
⇒side ,a = 2 units
now by Pythagoras theorem,
diagonal length = √((2)²+ (2)²
                         =2√2 units
so, radius of circle = 2√2 units
area of circle = π r²
                      =  π (2√2)²
                      =8π sq. units
so, area of circle = 8π sq. units.