The vertex of a parabola is at (3,2) and its directrix is $x-y+1=0$. Find the equation of latus rectum.

732 Views Asked by At

The distance of vertex from the directrix is $\sqrt 2$

Further, the slope of the axis is $-1$

The focus is $(h,k)$

Then $$\frac{h-3}{\frac{-1}{\sqrt 2}}=\sqrt 2$$ $$h=2$$

And $$\frac{k-2}{\frac{1}{\sqrt 2}}=\sqrt 2$$ $$k=3$$

The slope of latus rectum is 1

$$y-3=x-2$$$$x-y=-1$$

The answer given is $x-y=3$

What’s going wrong?

1

There are 1 best solutions below

2
On BEST ANSWER

$h$ and $k$ are not computed correctly. They should be,

$$h= 3+ \frac1{\sqrt2}\sqrt2=4,\>\>\>\>k=2-\frac1{\sqrt2}\sqrt2=1$$

which yields $x-y=3$.