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If 4l^2-5m^2+6l+1=0. Prove that lx+my+1=...

If `4l^2-5m^2+6l+1=0.` Prove that `lx+my+1=0` touches a definite circle. Find the centre & radius of the circle.

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A DAS GUPTA-Circles-EXERCISE
  1. If 4l^2-5m^2+6l+1=0. Prove that lx+my+1=0 touches a definite circle. F...

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  2. Find the equation of a circle whose diameter has the length 20 and the...

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  3. Find the equations of the circles touching y-axis at (0,3) and making ...

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  4. Find the equation of the circle which passes through the points (1,-2)...

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  5. The abscissa of the two points A and B are the roots of the equation x...

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  6. Let A = (0,1) and B=(-p/2,(q+1)/2) be two fixed points in a plane. Let...

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  7. Find the area of the triangle formed by the lines y = x, y= 2x, y=3x+4

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  8. Find the length of the chord x^2+y^2-4y=0 along the line x+y=1. Also f...

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  9. Prove that the circles x^2 + y^2-9 = 4r^2,r = 1,2,3 cut off equal int...

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  10. Determine all those values of p in R for which two chords can be drawn...

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  11. A circle of radius 2 lies in the first quadrant and touches both the a...

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  12. Show that the circles x^2+y^2-10 x+4y-20=0 and x^2+y^2+14 x-6y+22=0 to...

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  13. Two circles, each of radius 5 units, touch each other at (1, 2). If th...

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  14. Prove that x^2+y^2=a^2 and (x-2a)^2+y^2=a^2 are two equal circles touc...

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  15. The equation of the circle which touches the circle x^2+y^2-6x+6y+17 =...

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  16. Find the area of equilateral triangle inscribed in a circle x^2+y^2+2g...

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  17. Find the area of the triangle formed by the tangents from the point (4...

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  18. Find the equations of the circles passing through the point (-4,3) and...

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  19. The equation of one of the circles which touch the pair of lines x^2 -...

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  20. Lines 5x + 12 y -10=0 and 5x - 12y - 40=0touch a circle C(1) of diamet...

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  21. Find the equation of the circle passing through the points A(4,3). B(...

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