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Statement-I The equation of the directri...

Statement-I The equation of the directrix circle to the hyperbola `5x^(2)-4y^(2)=20` is `x^(2)+y^(2)=1`.
Statement-II Directrix circle is the locus of the point of intersection of perpendicular tangents.

A

Statement-I is true, Statement-II is also true, Statement-II is the correct explanation of Statement-I.

B

Statement-I is true, Statement-II is also true, Statement-II is not the correct explanation of Statement-I.

C

Statement-I is true, Statement-II is false.

D

Statement-I is false, Statement-II is true

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to analyze the two statements regarding the hyperbola given by the equation \(5x^2 - 4y^2 = 20\). ### Step 1: Rewrite the Hyperbola Equation First, we rewrite the equation of the hyperbola in standard form. The given equation is: \[ 5x^2 - 4y^2 = 20 \] Dividing the entire equation by 20, we get: \[ \frac{x^2}{4} - \frac{y^2}{5} = 1 \] From this, we can identify \(a^2 = 4\) and \(b^2 = 5\). ### Step 2: Find the Values of \(a\) and \(b\) Now, we calculate \(a\) and \(b\): \[ a = \sqrt{4} = 2, \quad b = \sqrt{5} \] ### Step 3: Use the Formula for the Directrix Circle The equation of the directrix circle for a hyperbola in standard form \(\frac{x^2}{a^2} - \frac{y^2}{b^2} = 1\) is given by: \[ x^2 + y^2 = a^2 - b^2 \] Substituting the values of \(a^2\) and \(b^2\): \[ x^2 + y^2 = 4 - 5 = -1 \] ### Step 4: Analyze the Result The equation \(x^2 + y^2 = -1\) does not represent a real circle since the left-hand side (which represents the sum of squares) cannot equal a negative number. Therefore, the equation of the directrix circle does not exist in the real number system. ### Conclusion for Statement I Since the equation \(x^2 + y^2 = 1\) is not valid, **Statement I is false**. ### Step 5: Evaluate Statement II Statement II claims that the directrix circle is the locus of the points of intersection of perpendicular tangents to the hyperbola. This is a known property of hyperbolas, and it is indeed true. ### Final Conclusion - **Statement I** is false. - **Statement II** is true. Thus, the correct option is that Statement I is false and Statement II is true.
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