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MathematicsCircleTangent & NormalMedium2 minPYQ_2016
MathematicsMediummultiple choice

The circleC1:x2+y2=3,with centre at O, intersects the parabolax2=2yat the point P in the first quadrant. Let the tangent to the circleC1at P touches other two circlesC2andC3atR2andR3, respectively. SupposeC2andC3have equal radii23and centresQ2and Q3, respectively. IfQ2andQ3lie on the y - axis, then

Question diagram: The circle C 1 : x 2 + y 2 = 3 , with centre at O, intersect

Options:(select one or more)

Answer:
A, B, C
Solution:


On solvingx2+y2=3andx2=2ywe get pointP2, 1
Equation of tangent at P
2 x+y=3
LetQ2be (0, k) and radius is23
2 0+k-32+1=23
k=9, -3Q3
Q2 0, 9andQ3 (0,-3) { C 2 : ( x0 ) 2 + ( y9 ) 2 =12 C 3 : ( x0 ) 2 + ( y+3 ) 2 =12
HenceQ2 Q3=12

a2+12=36
a=26
R2R3=2a=46
Perpendicular distance of origin O fromR2R3is equal to distance of O from tangent2x+y=3which is same as radius of circleC1= 3
Hence area ofΔOR2R3=12×R2R3 3=12. 46 . 3=62
Perpendicular Distance of P fromQ2Q3= 2
Area ofΔPQ2Q3=12×12×2=62

Stream:JEE_ADVSubject:MathematicsTopic:CircleSubtopic:Tangent & Normal
2mℹ️ Source: PYQ_2016

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