Question

Two concentric circles are radii 5cm and 3cm are drawn.find the length of the chord of the larger circle which touches the smaller circle.

Answer 1

let the radius of the bigger circle be 'R' and the radius of the smaller circle be 'r'.

It is given that R=5cm=OB and r=3cm=OD and AB is the chord whose length we have to find.

AD=BD and OD⊥AB(radius is perpendicular to a chord and it divides the chord into two equal parts)

therefore, ΔODB is a right angled triangle

where, OD²+BD²=OB²

            (3)²+BD²=(5)²

             9+BD²=25

             BD²=25-9

             BD²=16

             BD=4cm

       Since AD=BD=4cm

       therefore, AB=AD+BD

                       AB=4+4

                       AB=8cm

Answer 2

Step-by-step explanation:

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