Find the acute angle at which the curves $y=(x-2)^2$ and $y=-4+6x-x^2$ intersect.
Given curves are:
$y=(x-2)^2$
and
$y=-4+6x-x^2$
At the point of intersection,
$(x-2)^2=-4+6x-x^2$
$x^2-4x+4=-4+6x-x^2$
$2x^2-10x+8=0$
$x^2-5x+4=0$
$(x-1)(x-4)=0$
So,
$x=1$ or $x=4$
Now, slopes of the curves are:
For $y=(x-2)^2$,
$m_1=\frac{dy}{dx}=2(x-2)$
For $y=-4+6x-x^2$,
$m_2=\frac{dy}{dx}=6-2x$
At $x=1$,
$m_1=2(1-2)=-2$
$m_2=6-2(1)=4$
Angle between two curves is given by:
$\tan\theta=\left|\frac{m_2-m_1}{1+m_1m_2}\right|$
So,
$\tan\theta=\left|\frac{4-(-2)}{1+(-2)(4)}\right|$
$=\left|\frac{6}{1-8}\right|$
$=\left|\frac{6}{-7}\right|$
$=\frac{6}{7}$
Therefore,
$\theta=\tan^{-1}\left(\frac{6}{7}\right)$
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