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Maths Conic Sections Mix Single Correct MCQ
Published on: August 14, 2026

Straight line x + y = 18 and common tangents of the curve S 1 = x 2 + y 2 – 28x + 160 = 0 and S 2 = + – 1 = 0 form a triangle ABC in the first quadrant and S 3 = 0 is circumcircle of Δ ABC.

(i) Coordinates of centre of circle inscribed in the triangle ABC are –

A
[12 –2 , 10 –2 ] x 2 + y 2 – 16x – 20y + 156 = 0
B
[12 – , 10 – ] x 2 + y 2 – 10x – 8y + 156 = 0
C
[12 + 2 , 10 + 2 ] x 2 + y 2 – 8x – 10y + 156 = 0
D
[12 + , 10 + ] (ii) Equation of S 3 is – x 2 + y 2 – 20x – 16y + 156 = 0 (iii) Length of common chord of circle S 1 and S 2 is – Does not exist

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Text Solution

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The correct answer is:
C

Ans.

(i)

Sol. Area of Δ ABC = 8 sq. unit, 2s = 4 + 4 + 4 ,

r = = = 4 – 2

coordinate of centre

(8 + 4 – 2 , 6 + 4 – 2 )

=

(ii)

Sol. centre of circumcircle is (10, 8) and radius 2

So circle x 2 + y 2 – 20x – 16y + 156 = 0

(iii)

Sol. C 1 C 2 > r 1 + r 2

Since circles S 1 and S 3 does not intersect to each other so common chord does not exist.

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