Maths-
General
Easy
Question
Let A and B be two points on a parabola with vertex V such that VA is perpendicular to VB and θ is the angle between the chord VA and the axis of the parabola The value of is
The correct answer is:
we are given with two points A and B and asked to find the value of
y2=x , vertex is at the origin and axis is x−axis.
Let A has co-ordinates (a,b)
Now, according to question
tanθ=ab
Squaring both sides we get,
⟹tan2θ=a2b2
we know that b2=a
Hence, we get
⟹tan2θ=a1
⟹a=cot2θ
⟹b=cotθ
Similarly, for B
its co-ordinates are {cot(90−θ),cot2(90−θ)} as ∠AOB=90∘
⟹a=tan2θ
⟹b=tanθ
Now, applying distance formula we get
(∣VB∣)2(∣VA∣)2=tan4θ+tan2θcot4θ+cot2θ
(∣VB∣)2(∣VA∣)2=tan4θ(cot2θ+1)cot2θ(cot2θ+1)
(∣VB∣)2(∣VA∣)2=cot6θ
(∣VB∣)(∣VA∣)=cot³θ
we know that b2=a
Hence, we get
⟹tan2θ=a1
⟹a=cot2θ
⟹b=cotθ
Similarly, for B
its co-ordinates are {cot(90−θ),cot2(90−θ)} as ∠AOB=90∘
⟹a=tan2θ
⟹b=tanθ
Now, applying distance formula we get
(∣VB∣)2(∣VA∣)2=tan4θ+tan2θcot4θ+cot2θ
(∣VB∣)2(∣VA∣)2=tan4θ(cot2θ+1)cot2θ(cot2θ+1)
(∣VB∣)2(∣VA∣)2=cot6θ
(∣VB∣)(∣VA∣)=cot³θ
Therefore the value of is cot³θ
Related Questions to study
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The equation of the parabola whose vertex and focus lie on the axis of at distances a and from the origin, respectively, is
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Consider, where p is a real number, and
Statement‐l:: If line is a chord of circle , then line is not always adiameter ofcircle C.
Statement‐II :: If line is a diameter ofcircle , then line is not a chord ofcircle C.
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Statement‐II :: If line is a diameter ofcircle , then line is not a chord ofcircle C.
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The equation of the circle passing through the points (1, 0) and (0,1) and having the smallest radius is:
Therefore the correct option is Choice 3
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Therefore the correct option is Choice 3
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If a circle passes through the point (a, b) and cuts the circle orthogonally, then the equation of the locus of its centre is‐
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