The equation of the lines through the point $(3,2)$ which makes an angle of $45^{\circ}$ with the line $x-2…

The equation of the lines through the point $(3,2)$ which makes an angle of $45^{\circ}$ with the line $x-2 y=3$ are
  1. $3 x-y=7$ and $x+3 y=9$
  2. $x-3 y=7$ and $3 x+y=9$
  3. $x-y=3$ and $x+y=2$
  4. $2 x+y=7$ and $x-2 y=9$

Solution

Let $m_1$ be the slope of the line, which passes through the point $(3,2)$ and $m_2$ be the slope of $x-2 y=3$ $\therefore \quad m_2=\frac{- \text { Coefficient of } x}{\text { Coefficient of } y}$ $m_2=\frac{-1}{-2}$ $\Rightarrow \quad m_2=\frac{1}{2}$ Given that, the angle between lines is $45^{\circ}$ $\therefore \quad \tan 45^{\circ}=\left|\frac{m_1-m_2}{1+m_1 m_2}\right|$ $1= \pm\left|\frac{m_1-\frac{1}{2}}{1+m_1\left(\frac{1}{2}\right)}\right|$ When, $\quad 1=+\left(\frac{2 m_1-1}{2+m_1}\right)$ $\begin{aligned} \Rightarrow & & 2+m_1 & =2 m_1-1 \\ \Rightarrow & & m_1 & =3\end{aligned}$ and when $\quad 1=-\left(\frac{2 m_1-1}{2+m_1}\right)$ $\Rightarrow \quad m_1=\frac{-1}{3}$ Hence, equation a line passing through $(3,2)$ and having slope 3 is

Asked in: AP EAMCET 2021 (23 Aug Shift 2)

Practice more Straight Lines questions on Aicharya