Flag Analytical Geometry> A straight line L through the point (3, -...
question mark

A straight line L through the point (3, -2) is inclined at an angle 60° to the line 3x + y = 1 . If L also intersects the x-axis, then the equation of L is

Jayant Kumar , 12 Years ago
Grade 11
anser 1 Answers
Askiitians Tutor Team

To find the equation of the line L that passes through the point (3, -2) and is inclined at an angle of 60° to the line given by the equation 3x + y = 1, we can follow a systematic approach. First, we need to determine the slope of the line represented by the equation 3x + y = 1, and then use the angle information to find the slope of line L.

Finding the Slope of the Given Line

The equation of the line can be rewritten in slope-intercept form (y = mx + b) to easily identify its slope. Starting from the original equation:

  • 3x + y = 1
  • y = -3x + 1

From this, we see that the slope (m) of the line is -3.

Calculating the Slope of Line L

Line L is inclined at an angle of 60° to the line with a slope of -3. To find the slope of line L (let's call it m_L), we can use the formula for the tangent of the angle between two lines:

  • tan(θ) = |(m_L - m_1) / (1 + m_L * m_1)|

Here, m_1 is the slope of the given line (-3), and θ is 60°. The tangent of 60° is √3. Plugging in the values:

  • √3 = |(m_L + 3) / (1 - 3m_L)|

We can solve this equation for m_L. First, we consider two cases due to the absolute value.

Case 1: m_L + 3 = √3(1 - 3m_L)

Expanding and rearranging gives:

  • m_L + 3 = √3 - 3√3m_L
  • (1 + 3√3)m_L = √3 - 3
  • m_L = (√3 - 3) / (1 + 3√3)

Case 2: m_L + 3 = -√3(1 - 3m_L)

Similarly, we expand and rearrange:

  • m_L + 3 = -√3 + 3√3m_L
  • (1 - 3√3)m_L = -√3 - 3
  • m_L = (-√3 - 3) / (1 - 3√3)

Finding the Equation of Line L

Now that we have the slopes, we can use the point-slope form of the line equation, which is:

  • y - y_1 = m(x - x_1)

Substituting the point (3, -2) into the equation:

  • y + 2 = m_L(x - 3)

Finding the Intersection with the X-axis

To find where line L intersects the x-axis, we set y = 0:

  • 0 + 2 = m_L(x - 3)
  • 2 = m_L(x - 3)
  • x = 3 + 2/m_L

We can substitute the values of m_L from both cases to find the x-intercepts. After calculating, we can determine which slope gives a valid intersection point on the x-axis.

Finalizing the Equation

After substituting the slopes back into the point-slope form and simplifying, we will arrive at the final equation of line L. Depending on the calculations, you will find that the equation will be in the form:

  • y = mx + b

where m is the slope derived from either case and b is the y-intercept calculated from the point (3, -2).

By following these steps, you can derive the equation of line L that meets the specified conditions. If you need further clarification on any of the steps, feel free to ask!

ApprovedApproved
Last Activity: 11 Months ago
star
LIVE ONLINE CLASSES

Prepraring for the competition made easy just by live online class.

tv

Full Live Access

material

Study Material

removal

Live Doubts Solving

assignment

Daily Class Assignments