Question

The equations of the tangents drawn from the point (0, 1) to the circle $x^2+y^2-2x+4y=0$ are

• A. 2x - y + 1 = 0, x + 2y - 2 = 0
• B. 2x - y + 1 = 0, x + 2y - 2 = 0
• C. 2x - y - 1 = 0, x + 2y - 2 = 0
• D. 2x - y - 1 = 0, x + 2y + 2 = 0

Answer 1

The correct option is A 2x - y + 1 = 0, x + 2y - 2 = 0

Required equations are given by $S{S}_1=T^2$
$\Rightarrow (x^2+y^2-2x+4y)(1+4)=y-1\left(x\right)+2(y+1{)}^2$
$\Rightarrow 2x^2-2y^2-3x+4y+3xy-2=0$
$\Rightarrow (2x-y+1)(x+2y-2)=0.$