find the equation of the line which satisfy the given condition: Passing through (2, 2√3) and inclined with the x-axis at an angle of 75o.
find the equation of the line which satisfy the given condition: Passing through (2, 2√3) and inclined with the x-axis at an angle of 75o.

Given: point

    \[\left( \mathbf{2},\text{ }\mathbf{2}\surd \mathbf{3} \right)\]

 and

    \[\mathbf{\theta }\text{ }=\text{ }\mathbf{75}{}^\circ \]

Condition of line:

    \[\left( \mathbf{y}\text{ }\text{ }\mathbf{-y1} \right)\text{ }=\text{ }\mathbf{m}\text{ }\left( \mathbf{x}\text{ }\text{ }\mathbf{-x1} \right)\]

where,

    \[\mathbf{m}\text{ }=\text{ }\mathbf{incline}\text{ }\mathbf{of}\text{ }\mathbf{line}\text{ }=\text{ }\mathbf{tan}\text{ }\mathbf{\theta }\text{ }\mathbf{and}\text{ }\left( \mathbf{x1},\text{ }\mathbf{y1} \right)\]

are the focuses through which line passes

 

    \[\therefore \mathbf{m}\text{ }=\text{ }\mathbf{tan}\text{ }\mathbf{75}{}^\circ \]

    \[\mathbf{75}{}^\circ \text{ }=\text{ }\mathbf{45}{}^\circ \text{ }+\text{ }\mathbf{30}{}^\circ \]

Applying the eqn:

NCERT Solutions for Class 11 Maths Chapter 10 – Straight Lines image - 14

We realize that the point (x, y) lies on the line with incline m through the decent point (x1, y1), if and provided that, its directions fulfill the condition

    \[\mathbf{y}\text{ }\text{ }\mathbf{-y1}\text{ }=\text{ }\mathbf{m}\text{ }\left( \mathbf{x}\text{ }\text{ }\mathbf{-x1} \right)\]

Then, at that point,

    \[\mathbf{y}\text{ }\text{ }\mathbf{-2}\surd \mathbf{3}\text{ }=\text{ }\left( \mathbf{2}\text{ }+\text{ }\surd \mathbf{3} \right)\text{ }\left( \mathbf{x}\text{ }\text{ }\mathbf{-2} \right)\]

    \[\mathbf{y}\text{ }\text{ }\mathbf{-2}\surd \mathbf{3}\text{ }=\text{ }\mathbf{2}\text{ }\mathbf{x}\text{ }\text{ }\mathbf{-4}\text{ }+\text{ }\surd \mathbf{3}\text{ }\mathbf{x}\text{ }\text{ }\mathbf{-2}\text{ }\surd \mathbf{3}\]

    \[\mathbf{y}\text{ }=\text{ }\mathbf{2}\text{ }\mathbf{x}\text{ }\text{ }\mathbf{-4}\text{ }+\text{ }\surd \mathbf{3}\text{ }\mathbf{x}\]

    \[\left( \mathbf{2}\text{ }+\text{ }\surd \mathbf{3} \right)\text{ }\mathbf{x}\text{ }\text{ }\mathbf{-y}\text{ }\text{ }\mathbf{-4}\text{ }=\text{ }\mathbf{0}\]

The condition of the line is

    \[\left( \mathbf{2}\text{ }+\text{ }\surd \mathbf{3} \right)\text{ }\mathbf{x}\text{ }\text{ }\mathbf{-y}\text{ }\text{ }\mathbf{-4}\text{ }=\text{ }\mathbf{0}.\]