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Equation of tangent to circle x2+y2-2x-4y-4=0 and parallel to the line 3x+4y=0 is????

Ishita singhal , 6 Years ago
Grade 11
anser 1 Answers
kkbisht

Last Activity: 6 Years ago

circle :x2+y2-2x-4y-4=0
Centre: (1,2)    radius : \sqrt{}1+4+4 = 3
Let the equation  of the tangent is : y=mx+c
as the tangent is parallel to the line 3x+4y=0 => m=-3/4
Therefore the tangent is 4y+3x-4c=0
Length of perpendicular from centre( 1,2) to the tangent 4y+3x-4c=0  must be equal to radius= 3
ie.   ( 4.2+3.1-4c)/\sqrt{}42 +32 = 3   =. 8+3-4c=5.3=15 ==>c= -1
Therefore Eqn of tangent is 4y+3x+4=0
By kkbisht

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