Q.

Let ABCD and AEFG be squares of sides 4 and 2 units respectively. the point E is on the line segment AB and the point F is on the diagonal AC. Then the radius r of the circle passing through the point F and touching the line segments BC and CD satisfies :          [2024]

1 2r2–4r+1=0  
2 r2–8r+8=0  
3 r = 1  
4 2r2–8r+7=0  

Ans.

(2)

Let r be the radius of circle and centre at C(r, r).

Then, FC2 = r2

⇒   (r –2)2 + (r – 2)2 = r2 

⇒   r2 – 8r + 8 = 0.