Q40 / 90 · JEE Main 2024 (30 Jan Shift 2) · Mathematics

Consider two circles C1:x2+y2=25 and C2:(x-α)2+y2=16, where α∈(5,9). Let the angle between the two radii (one to each circle) drawn from one of the intersection points of C1and C2 be sin-1638. If the length of common chord of C1 and C2 is β, then the value of (αβ)2 equals _________.

Correct answer: 1575

Solution

Given,

C1:x2+y2=25, C2:(x-α)2+y2=16 and 5<α<9

Now, plotting the diagram we get,

Figure

Also, given sinθ=638

Now, from the above diagram, finding the area of  ΔOAP we get, 

ΔOAP=12×αβ2=12×5×4sinθ

⇒αβ=40×638

⇒αβ=5×63

⇒(αβ)2=25×63=1575

Hence, the correct answer is 1575.

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