31. What will be the area of the largest square that can be cut out of a circle of radius 10 cm?
(a) 100 cm²
(b) 200 cm²
(c) 300 cm²
(d) 400 cm²
Diagonal of square = diameter of circle = 20 cm.
So side = \( \tfrac{20}{\sqrt{2}} = 10\sqrt{2} \).
Area = (10√2)² = 200 cm².