NIMCET 2015 — Mathematics PYQ
NIMCET | Mathematics | 2015The locus of the mid-point of all chords of the parabola y2=4x, which are drawn through its vertex is:
Choose the correct answer:
- A.
y2=8x
- B.
y2=2x
(Correct Answer) - C.
x2+4y2=16
- D.
x2=2y
y2=2x
Explanation
1. Identify the Points
The given parabola is y2=4x.
-
The vertex of this parabola is V(0,0).
-
Let P(x1,y1) be any point on the parabola. Since P lies on y2=4x, it satisfies:
y12=4x1
2. Define the Mid-point
Let M(h,k) be the mid-point of the chord VP, where V is the vertex (0,0) and P is (x1,y1).
Using the mid-point formula:
3. Substitute into the Parabola Equation
Now, substitute the values of x1 and y1 into the equation of the parabola (y12=4x1):
4. Simplify and Find the Locus
Divide both sides by 4:
To find the final equation of the locus, replace (h,k) with (x,y):
Conclusion
The locus of the mid-points of the chords drawn through the vertex of the parabola y2=4x is y2=2x.
Correct Option: (b)
Explanation
1. Identify the Points
The given parabola is y2=4x.
-
The vertex of this parabola is V(0,0).
-
Let P(x1,y1) be any point on the parabola. Since P lies on y2=4x, it satisfies:
y12=4x1
2. Define the Mid-point
Let M(h,k) be the mid-point of the chord VP, where V is the vertex (0,0) and P is (x1,y1).
Using the mid-point formula:
3. Substitute into the Parabola Equation
Now, substitute the values of x1 and y1 into the equation of the parabola (y12=4x1):
4. Simplify and Find the Locus
Divide both sides by 4:
To find the final equation of the locus, replace (h,k) with (x,y):
Conclusion
The locus of the mid-points of the chords drawn through the vertex of the parabola y2=4x is y2=2x.
Correct Option: (b)