Animated Solution for Mathematics - Conic Sections: Statement-1 : An equation of a common tangent to the parabola y2=163x and the ellipse 2x2+y2=4 is y=2x+23
Statement-2 : If the line y=mx+m43,(m=0) is a common tangent to the parabola y2=163x and the ellipse 2x2+y2=4, then m satisfies m4+2m2=24
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Visualized Solution
Visualizing the Curves
Given Curves:
Parabola: y2=163x
Ellipse: 2x2+y2=4
Objective: Find the equation of the common tangent and verify the statements.
Standardizing the Ellipse
Divide 2x2+y2=4 by 4:
42x2+4y2=1⇒2x2+4y2=1
Standard form: a2x2+b2y2=1
Comparing, we get a2=2 and b2=4.
Tangent Condition for Ellipse
Condition for tangency to ellipse a2x2+b2y2=1:
y=mx±a2m2+b2
Substituting a2=2 and b2=4:
y=mx±2m2+4…(1)
Standardizing the Parabola
Parabola: y2=163x
Standard form: y2=4ax
Comparing: 4a=163⇒a=43
Tangent Condition for Parabola
Condition for tangency to parabola y2=4ax:
y=mx+ma
Substituting a=43:
y=mx+m43…(2)
Equating the Constants
For a common tangent, equate the constant terms from (1) and (2):
m43=±2m2+4
Squaring Both Sides
Squaring both sides to remove the square root:
m216×3=2m2+4
m248=2m2+4
Rearranging the Equation
Multiply by m2:
48=2m4+4m2
Rearrange and divide by 2:
2m4+4m2−48=0
m4+2m2−24=0
Solving for Slope m
Factorize the quadratic in m2:
Let t=m2, then t2+2t−24=0
(t+6)(t−4)=0⇒(m2+6)(m2−4)=0
Since m2=−6 (as m is real), we have m2=4
Therefore, m=±2
Verifying Statement 1
Substitute m=2 into the tangent equation y=mx+m43:
y=2x+243
y=2x+23
This matches Statement-1 perfectly.
Conclusion: Statement-1 is true, Statement-2 is true, and Statement-2 is the correct explanation for Statement-1.
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The Sigma Insight: Equation of Tangent and Normal
Solution Diagram
Analyzing the Setup
Imagine you are standing on a coordinate plane, looking at two distinct geometric entities: a parabola y2=163x and an ellipse 2x2+y2=4. They seem like strangers, living in different parts of the plane, but they share a secret connection—a common tangent line.
Our mission today is to uncover this line and prove the relationship between these two curves.
Standardizing the Ellipse
First, we must bring our ellipse into the light. The equation 2x2+y2=4 is not quite in its standard form.
To reveal its true nature, we divide the entire equation by 4, yielding:
2x2+4y2=1
Now, comparing this to the standard form a2x2+b2y2=1, we identify a2=2 and b2=4. This is the foundation of our ellipse.
The Parabola's Identity
Next, we turn to the parabola y2=163x. Comparing this to the standard form y2=4ax, we find 4a=163, which simplifies beautifully to a=43.
We now have the parameters for both curves.
The Bridge of Tangency
A line y=mx+c is a common tangent if it satisfies the condition of tangency for both curves. For the ellipse, the condition is c2=a2m2+b2.
Substituting our values, we get:
c2=2m2+4
For the parabola, the condition is c=ma. Substituting a=43, we get:
c=m43
Now, we bridge the two worlds by equating the constant c. By substituting the parabola's c into the ellipse's condition, we get:
(m43)2=2m2+4
The Algebraic Triumph
Now, let's solve this. Squaring the left side gives:
m216×3=m248
So, m248=2m2+4. Multiplying by m2 and rearranging, we arrive at:
2m4+4m2−48=0
Dividing by 2, we get the elegant polynomial:
m4+2m2−24=0
This is the exact condition mentioned in Statement-2! Treating this as a quadratic in m2, we factor it as (m2+6)(m2−4)=0.
Since m2 must be positive for a real slope, we find m2=4, leading to m=±2.
Substituting m=2 back into our tangent equation y=mx+m43, we get y=2x+243, which simplifies to:
y=2x+23
This confirms Statement-1. We have successfully navigated the geometry and the algebra to find the common tangent. The beauty of this problem lies in how two seemingly different curves can be linked by a single, elegant line.