Ans: 44

Have you learn pythagoras? If not theres still other ways to find the diameter.

Divide the square into 4 identical right-angled isosceles triangles.

These triangles have height and base both equal to the radius of the circle.


Area of each right angled triangle

= 98 cm² ÷ 4
= 24.5 cm²

But area of each right angled triangle also

= ½ x base x height
= ½ radius of circle x radius of circle

So,

½ radius of circle x radius of circle = 24.5 cm²

radius of circle x radius of circle = 24.5 cm² x 2 = 49cm²

(This is the same as two triangles combined to form a square with sides equal in length to the radius.)


Radius of circle = √49 cm = 7cm
(Or realise that 7 x 7 = 49 so the radius must be 7cm)


Circumference of circle (2πr)

= 2 x 22/7 cm x 7 cm

= 44 cm