A circle touches  two  adjacent  sides of a rectangle  AB and AD at Points P and Q   respectively. Third  vertex C of the  rectangle  lies on the circle . The  length  of perpendicular  from vertex C to  the chord PQ  is  5. Find the  area of rectangle..

Dear Student, 

Let C lie on the arc C₁C₂. Label the 90° and 45° angles


Since PQ subtends a central angle of 90°, the inscribed angle PCQ must be 45°

Let ∠BCP = α. Label the remaining angles in terms of α: 


Draw the perpendicular from C to PQ. Let E be the point of intersection. 

∠ECQ = α 
∠PCE = 45-α 

Since EC = 5 and ∠ECQ = α, CQ = 5/cosα. 
Since ∠QCD = 45-α, CQ = CD/cos(45-α). 
5/cosα = CD/cos(45-α) 
CD = 5·cos(45-α)/cosα 

Similarly, BC = 5·cosα/cos(45-α). 
Area of rectangle ABCD = CD×BC = 25 square units.
Regards

 

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