Question

The circle with equation x² + y² – 6x – 8y + 8 = 0 doesn't lie in –

• A. 3rd and 4th quadrant
• B. 2nd and 3rd quadrant
• C. 3rd quadrant only
• D. 4th quadrant only

Answer 1

Answer: (C)

3rd quadrant only

Answer 2

x² + y² – 6x – 8y + 8 = 0 ̃ C(3,4) & r =$\sqrt{9 + 16 - 8} = \sqrt{17}$

Intersection point with x-axis put y = 0

x² – 6x + 8 = 0 ̃ x² – 4x – 2x + 8 = 0

x = 4,2 both x positive

Intersection point with y-axis put x = 0

y² – 8y + 8 = 0 ̃ y = $\frac{8 \pm \sqrt{64 - 4 \times 8}}{2}$ ̃ y ± $\sqrt{2}$

both y positive does not lie in 3^rd quadrant