For the parabola represented in the parameteric form by $x=t^2+t+1$ and $y=t^2-t+1$, the length of latus…
For the parabola represented in the parameteric form by $x=t^2+t+1$ and $y=t^2-t+1$, the length of latus rectum is
- $2$
- $3$
- $1 / 2$
- $8$
Solution
Given,
$\begin{aligned} & x=t^2+t+1 \\ & y=t^2-t+1 \Rightarrow x+y=2\left(t^2+1\right)\end{aligned}$
and $\quad(x-y)=2 t$ ...(i)
$\Rightarrow \quad t=\frac{x-y}{2}$ ...(ii)
From Eqs. (i) and (ii),
$x+y=2\left[\frac{(x-y)^2}{4}+1\right]$
$\begin{array}{ll}\Rightarrow & 2(x+y)=(x-y)^2+4 \\ \Rightarrow & (x-y)^2=2(x+y-2)\end{array}$
$Y^2=2 X$
where, $\quad Y=x-y$
and $\quad X=x+y-2$
$\therefore$ Length of latus rectum $=2$
Asked in: AP EAMCET 2022 (07 Jul Shift 1)
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