JEE Challenger
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Perpendicular Tangents from a Point to a Circle

Tangents are drawn from the point (17,7)(17, 7) to the circle x2+y2=169x^2 + y^2 = 169.

STATEMENT-1 : The tangents are mutually perpendicular.
because
STATEMENT-2 : The locus of the points from which mutually perpendicular tangents can be drawn to the given circle is x2+y2=338x^2 + y^2 = 338.

Options

A

Statement-1 is True, Statement-2 is True; Statement-2 is a correct explanation for Statement-1

Correct
B

Statement-1 is True, Statement-2 is True; Statement-2 is NOT a correct explanation for Statement-1

C

Statement-1 is True, Statement-2 is False

D

Statement-1 is False, Statement-2 is True

Topics & Concepts

Step-by-Step Solution

To determine the validity of the statements, we analyze the properties of the given circle and its director circle:

  1. Analysis of Statement-2:
    The given circle is:
    x2+y2=169x^2 + y^2 = 169
    The radius of the circle is r=169=13r = \sqrt{169} = 13.

    The locus of points from which mutually perpendicular tangents can be drawn to a circle is known as its director circle.
    For a circle of radius rr centered at the origin, the equation of its director circle is given by:
    x2+y2=2r2x^2 + y^2 = 2r^2
    Substituting r2=169r^2 = 169:
    x2+y2=2(169)=338x^2 + y^2 = 2(169) = 338
    Therefore, the locus of points from which mutually perpendicular tangents can be drawn to the circle is indeed x2+y2=338x^2 + y^2 = 338.
    Hence, Statement-2 is True.

  2. Analysis of Statement-1:
    We are given the point P(17,7)P(17, 7). Let us check if this point lies on the director circle found above:
    x2+y2=172+72=289+49=338x^2 + y^2 = 17^2 + 7^2 = 289 + 49 = 338
    Since the coordinates of the point (17,7)(17, 7) satisfy the equation of the director circle, the tangents drawn from this point to the given circle x2+y2=169x^2 + y^2 = 169 must be mutually perpendicular.
    Hence, Statement-1 is True.

  3. Conclusion:
    Statement-2 correctly defines the director circle, which is the direct mathematical reason that the tangents drawn from (17,7)(17, 7) are mutually perpendicular. Therefore, Statement-2 is the correct explanation for Statement-1.

Thus, the correct choice is A.