Two circles of radii 4 cm and 9 cm respectively touch each other externally at a point and a common tangent touches them at the points P and Q respectively. Then the area of a square with one side PQ, is
$$PQ= \sqrt{(Distance. between. centers)^2-(r_1-r_2)^2}$$
$$PQ= \sqrt{(4+9)^2-(9-4)^2}$$
= 12
Area of req. square = $$12^2$$ = 144
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