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Vijay Sharma

· started a discussion

· 1 Months ago

WHAT IS AP WHAT IS AQ....can't u upload a figure??

Question:
The length of the common chord of two circle of radii 15 cm and 20 cm whose centres are 25 cm apart, is (in cm) :
Options:
A) 24
B) 25
C) 15
D) 20
Solution:
Ans: (a)

Given AP = 15 cm, AQ = 20 cm and PQ = 25 cm

Let OQ be y cm then OP = (25-y) cm

In \(\Delta\)APO, AO2 = (15)2 - (25-y)2

In \(\Delta\)AQO, AO2 = (20)2 - y2

From (i) and (ii)

225 - 625 - y2 + 50y = 400 - y2

y = 16

Hence from (i) AO2 = (15)2 - (25 - 16)2

AO2 = 225 - 81

AO2 = 144

AO = 12 cm

Hence, length of common chord AB = 12 x 2 = 24 cm

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