Equations of two diameters of a circle are 2x-3y=5 and 3x-4y=7. The line joining the points (- 227,-4 ) and (- 17,3 ) intersects the circle at only one point P( , ). Then, 17 - is equal to .
Answer
2
Solution
Centre = meeting point of the diameters: 2x-3y=5, 3x-4y=7 (1,-1)
AB: slope = 3+4- 17+ 227= 73 ⇒ 7x-3y+10=0
∵ AB meets the circle at only one point ⇒ AB is a tangent, P = foot of perpendicular from C
[figure]
-17= +1-3=- 7(1)-3(-1)+1072+32=- 1029
⇒ =1- 7029=- 4129, =-1+ 3029= 129
∴ 17 - = 17+4129=2
Answer: 2