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
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