KCET2010MathematicsCircle
Equation of the circle centred at (4,3) touching the circle x²+y²=1 externally, is
Options
- Ax²+y²-8 x-6 y+9=0
- Bx²+y²+8 x+6 y+9=0
- Cx²+y²+8 x-6 y+9=0
- Dx²+y²-8 x+6 y+9=0
Correct answer
A. x²+y²-8 x-6 y+9=0
Step-by-step solution
Given that, equation of circle x²+y²=1 Centre at O (0,0) Radius = OA =1 Also, the centre of another circle C(4,3) both circle touch externally. Then, distance between centres = OC. = (4-0)²+(3-0)² = 16-9 =5 Now, AC = OC - OA A C=5-1=4 So, the radius of other circle is 4 . Now, the equation of other circle touch externally to the circle x ²+ y ²=1 is, gathered (x-4)²+(y-3)²=16 x²+y²-8 x-6 y+9=0 gathered