Multiple choice

𝐶 is a circle represented by 𝑥² + 𝑦²﹣8𝑥﹣8𝑦 + 16 = 0. The straight line joining the origin to the center of the circle is extended such that it intersects the circle at a point (𝑝,𝑞). If a tangent to the circle is drawn at (𝑝,𝑞), then what is the area, in sq. units, of the triangle formed by the tangent with the coordinate axes?

  1. 16(3+2√2)

  2. 16(√2+1)

  3. 8(3+√2)

  4. None

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A Correct answer
Explanation

The circle is (x-4)^2 + (y-4)^2 = 16. Center is (4,4), radius is 4. The line from origin to center is y=x. Intersection points (p,q) are found by substituting y=x into the circle equation: 2x^2 - 16x + 16 = 0 => x^2 - 8x + 8 = 0. Roots are 4 +/- 2*sqrt(2). Point (p,q) is (4+2*sqrt(2), 4+2*sqrt(2)). Tangent equation at (x0,y0) is (x-4)(x0-4) + (y-4)(y0-4) = 16. Plugging in (p,q) gives (x-4)(2*sqrt(2)) + (y-4)(2*sqrt(2)) = 16 => x+y = 8+4*sqrt(2). Intercepts are 8+4*sqrt(2). Area = 1/2 * (8+4*sqrt(2))^2 = 16(3+2*sqrt(2)).