Question

What is the length of the common chord of two circles of radii 12 cm and 16 cm, where distance between their centers is 20 cm?

A 6.4 cm Correct Answer Incorrect Answer
B 19.2 cm Correct Answer Incorrect Answer
C 9.4 cm Correct Answer Incorrect Answer
D 12.8 cm Correct Answer Incorrect Answer

Solution

Let radius of circle with center  A   be  r 1   and circle with center  C   be  r 2 , and  AC = d be the distance between the centers. We know the length of the common chord of two circles = 2r1r2/d = 2 * 12 * 16/20 = 19.2 cm

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