Grade 7

A square on the centre

A circle of radius 6 cm and a square balanced on its centre -- the only number on the page is hiding in plain sight.

1
The shaded square
A circle has radius $6$ cm. A square stands in the top-right quarter of the circle: its bottom-left corner sits exactly at the centre of the circle, and its top-right corner lies on the circle's edge. What is the area of the square, in square centimetres?