Question Number 5822 by Rasheed Soomro last updated on 30/May/16
$$\mathcal{P}{rove}\:{that}\:{among}\:{all}\:\boldsymbol{{triangles}}, \\ $$$${which}\:{have}\:{same}\:\boldsymbol{{circum}}-\boldsymbol{{radius}}, \\ $$$${the}\:\boldsymbol{{equilateral}}\:\boldsymbol{{triangle}}\:{has} \\ $$$$\boldsymbol{{maximum}}\:\boldsymbol{{area}}. \\ $$