Question
If radii of two concentric circles are 4 cm and 5 cm,
then the length of eachchord of one circle which is tangent to the other circle isSolution
We have two concentric circles with radii 4 cm and 5 cm. A chord of the larger circle is tangent to the smaller circle. We need to find its length. Identify Key Distances The radius of the larger circle = 5 cm The radius of the smaller circle = 4 cm (this is also the perpendicular distance from the center to the chord). The perpendicular from the center bisects the chord. Use Pythagoras Theorem In the right triangle formed: 
Hence Full Chord Length = AB=2×MB=2×3=6 cm
114, 134, 174, 254, 414, ?Â
10, 20, 60, 300, ?, 23100
What will come in place of the question mark (?) in the following series?
17, 138, 307, 532, ?, 1182
6848 + 9215 – 7295 - ? = 5945 – 3244
12, 24, 46, 78, 120, ?
What will come in place of the question mark (?) in the following series?
121, 110, 97, ?, 61, 38
32, 42, 62, 92, ?, 182
418, 406, 430, 382, 478, ?, 670
11          20          ?             64          112        192
...250, 279, 311, 349, 396, ?
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