Find the equation of the circle circumscribing the rectangle whose sides are x – 3y = 4, 3x + y = 22, x – 3y = 14 and 3x + y = 62.
Find the equation of the circle circumscribing the rectangle whose sides are x – 3y = 4, 3x + y = 22, x – 3y = 14 and 3x + y = 62.

The sides

    \[\begin{array}{*{35}{l}} x\text{ }-\text{ }3y\text{ }=\text{ }4\text{ }\ldots .\text{ }\left( 1 \right)  \\ 3x\text{ }+\text{ }y\text{ }=\text{ }22\text{ }\ldots \text{ }\left( 2 \right)  \\ x\text{ }-\text{ }3y\text{ }=\text{ }14\text{ }\ldots .\text{ }\left( 3 \right)  \\ 3x\text{ }+\text{ }y\text{ }=\text{ }62\text{ }\ldots \text{ }\left( 4 \right)  \\ \end{array}\]

assuming A, B, C, D as the vertices of the square and solving the lines, we get :

A = (7, 1)

B = (8, – 2)

C = (20, 2)

D = (19, 5)

the equation of the circle with diagonal AC as diameter is given by

    \[\begin{array}{*{35}{l}} (x\text{ }-\text{ }{{x}_{1}})\text{ }(x\text{ }-\text{ }{{x}_{2}})\text{ }+\text{ }(y\text{ }-\text{ }{{y}_{1}})\text{ }(y\text{ }-\text{ }{{y}_{2}})\text{ }=\text{ }0  \\ \left( x\text{ }-\text{ }7 \right)\text{ }\left( x\text{ }-\text{ }20 \right)\text{ }+\text{ }\left( y\text{ }-\text{ }1 \right)\text{ }\left( y\text{ }-\text{ }2 \right)\text{ }=\text{ }0  \\ \end{array}\]

simplyfing we get

    \[{{x}^{2}}~+\text{ }{{y}^{2}}~-\text{ }27x\text{ }-\text{ }3y\text{ }+\text{ }142\text{ }=\text{ }0\]

∴The equation of the circle is

    \[{{x}^{2}}~+\text{ }{{y}^{2}}~-\text{ }27x\text{ }-\text{ }3y\text{ }+\text{ }142\text{ }=\text{ }0\]