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  The Rectangle At The Corner  -  Hint

Construct a right-angled triangle in the circle and use Pythagoras' Theorem. 

For any right-angled triangle, Pythagoras' Theorem states that the squares of the two sides adjacent to the right angle equal the square of the hypotenuse. If A and B are the lengths of the two sides and C is the length of the hypotenuse, then
A squared + B squared = C squared. 


 
 
 
 
 
 

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