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Coordinate Geometry

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  • (x−2)² + (y+3)² = 25
  • x-int = (4, 0), y-int = (0, 3)
  • (−1−5)/(4−1) = −6/3 = −2
  • Tangent eqn: 3x+4y = 25
  • Substitute y = 2x−1 ⇒ x²+(2x−1)²=10 ⇒ x=1, −1 ⇒ (1, 1), (−1, −3)
  • Perpendicular distance = |0−4|/√2 = 2√2 ≠ √8 ⇒ Not tangent
  • y+2 = 2(x−1) ⇒ y = 2x − 4
  • Same slope ⇒ y+3 = (2/5)(x−4)
  • √((8−2)²+(9−3)²) = √72 = 6√2
  • y−3 = 4(x−2) ⇒ y = 4x − 5
  • (3²+4²)=25 ⇒ on the circle
  • Using slope equality ⇒ (k−2)/(3−1) = (6−k)/(5−3) ⇒ k = 4
  • Center = (2, −3), r = √(4+9+3) = √16 = 4
  • Midpoint = ((−4+10)/2, (7+−5)/2) = (3, 1)
  • Center = (2, 6), r = √((6−(−2))²+(8−4)²)/2 = √80/2 = 2√5 ⇒ (x−2)² + (y−6)² = 20
  • y−3 = 2(x−2) ⇒ y = 2x − 1