Find the equations of the lines that pass through the point [tex]\((2,3)\)[/tex] and make an angle of [tex]\(45^\circ\)[/tex] with the line [tex]\(x - 3y - 2 = 0\)[/tex].



Answer :

To find the equations of the lines passing through the point [tex]\((2,3)\)[/tex] and making an angle of [tex]\(45^\circ\)[/tex] with the line [tex]\(x - 3y - 2 = 0\)[/tex], follow these steps:

1. Convert the given line to slope-intercept form:
The given line is [tex]\(x - 3y - 2 = 0\)[/tex]. To find the slope, rearrange it to the slope-intercept form [tex]\(y = mx + c\)[/tex]:

[tex]\[ x - 3y - 2 = 0 \implies 3y = x - 2 \implies y = \frac{1}{3}x - \frac{2}{3} \][/tex]

Therefore, the slope ([tex]\(m_1\)[/tex]) of the given line is [tex]\(\frac{1}{3}\)[/tex].

2. Determine the slopes of the lines making [tex]\(45^\circ\)[/tex] with the original slope:
The slopes of the lines making an angle [tex]\(\theta = 45^\circ\)[/tex] with a line of slope [tex]\(m_1\)[/tex] can be found using the formulas:

[tex]\[ m_2 = \frac{m_1 + \tan(\theta)}{1 - m_1 \tan(\theta)} \][/tex]
[tex]\[ m_3 = \frac{m_1 - \tan(\theta)}{1 + m_1 \tan(\theta)} \][/tex]

Given [tex]\(\theta = 45^\circ\)[/tex], [tex]\(\tan(45^\circ) = 1\)[/tex].

Thus, the slopes [tex]\(m_2\)[/tex] and [tex]\(m_3\)[/tex] are calculated as:

[tex]\[ m_2 = \frac{\frac{1}{3} + 1}{1 - \frac{1}{3} \cdot 1} = \frac{\frac{4}{3}}{\frac{2}{3}} = 2 \][/tex]
[tex]\[ m_3 = \frac{\frac{1}{3} - 1}{1 + \frac{1}{3} \cdot 1} = \frac{-\frac{2}{3}}{\frac{4}{3}} = -\frac{1}{2} \][/tex]

3. Find the y-intercepts of the new lines passing through [tex]\((2,3)\)[/tex]:
Using the point-slope form of the equation of a line, [tex]\(y - y_1 = m(x - x_1)\)[/tex], we can find the y-intercepts ([tex]\(b\)[/tex]) for both lines.

For the line with slope [tex]\(m_2 = 2\)[/tex]:
[tex]\[ y - 3 = 2(x - 2) \implies y - 3 = 2x - 4 \implies y = 2x - 1 \][/tex]
Thus, the y-intercept [tex]\(b_2\)[/tex] is [tex]\(-1\)[/tex].

For the line with slope [tex]\(m_3 = -\frac{1}{2}\)[/tex]:
[tex]\[ y - 3 = -\frac{1}{2}(x - 2) \implies y - 3 = -\frac{1}{2}x + 1 \implies y = -\frac{1}{2}x + 4 \][/tex]
Thus, the y-intercept [tex]\(b_3\)[/tex] is [tex]\(4\)[/tex].

4. Write the equations of the lines:
The equations of the lines passing through [tex]\((2,3)\)[/tex] and making an angle of [tex]\(45^\circ\)[/tex] with the line [tex]\(x - 3y - 2 = 0\)[/tex] are:

[tex]\[ \text{Line 1: } y = 2x - 1 \][/tex]
[tex]\[ \text{Line 2: } y = -\frac{1}{2}x + 4 \][/tex]

To summarize, the equations of the two lines are:
[tex]\[ y = 2x - 1 \][/tex]
[tex]\[ y = -\frac{1}{2}x + 4\][/tex]