The length of latusrectum of parabola $y^2+8 x-2 y+17=0$ is

The length of latusrectum of parabola $y^2+8 x-2 y+17=0$ is
  1. $2$
  2. $4$
  3. $8$
  4. $16$

Solution

The given equation of the parabola is $\Rightarrow \quad \begin{array}{ll} & y^3+8 x-2 y+17=0 \\ \Rightarrow \quad & (y-1)^2+8 x+16=0 \\ & (y-1)^2=-8(x+2)\end{array}$ Length of the latusrectum $=4 a=8$

Asked in: AP EAMCET 2001

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