Circle And System Of Circles Question 320
Question: If the equation of one tangent to the circle with centre at (2, -1) from the origin is $ 3x+y=0 $ , then the equation of the other tangent through the origin is
Options:
A) $ 3x-y=0 $
B) $ x+3y=0 $
C) $ x-3y=0 $
D) $ x+2y=0 $
Show Answer
Answer:
Correct Answer: C
Solution:
Centre is $ (2,\ -1) $ . Therefore $ r=| \frac{3(2)-1}{\sqrt{10}} |\ =\frac{5}{\sqrt{10}} $ Now draw a perpendicular on $ x-3y=0 $ , we get $ r=| \frac{2-3(-1)}{\sqrt{10}} |\ =\frac{5}{\sqrt{10}} $ .
BETA
