HKIMO 2018 Grade 6 National Final (Heat) Set 03 Question 20

A circle has area 12.56 cm². Its radius equals the diagonal of a square. Find the area of the square, in cm². Take $\pi=3.14$.

Source glossary (English–Vietnamese): Area: diện tích; Circle: hình tròn; Radius: bán kính; Diagonal: đường chéo; Square: hình vuông.