JEE MainMathematicsParabolaMCQ+4 / −1
A line passing through the point , touches the parabola at the point in the first quadrant. The area, of the region bounded by the line , parabola and the -axis, is :
- A3
- B
- C
- D2
View written solutionFree
Correct answer: C
- Write the parabola in standard form
Given This is a right-opening parabola with vertex at .
The point of contact lies in the first quadrant, so let
- Equation of tangent to the parabola at parameter
For the parabola with and , the tangent at can be written using differentiation.
From differentiate: So at , slope of tangent is
Hence tangent at is
- Use the fact that tangent passes through
Substitute into the tangent equation: So, Multiply by : Since ,
Therefore,
- Find equation of line
Slope of : Hence equation is Or in terms of as a function of :
- Identify the bounded region
The region is bounded by:
- the line segment
- the parabola from to
- the -axis from to
It is convenient to integrate with respect to from to .
For a fixed :
- left boundary is the line:
- right boundary is the parabola:
So area is
Simplify:
- Evaluate the integral
- Check options
The area is So the correct option is C.
- Comparison with stored answer
Stored correct answer: C
Our derived answer: C
So they agree.
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