Math Problem Statement

Given the coordinates of the points A(−3, −1), B(4, 1) and C(3, −5) find the product of the slope and y-intercept for the line perpendicular to BC and passing through A

Solution

Problem Breakdown:

We need to determine the product of the slope and yy-intercept of the line:

  1. Perpendicular to BC (line passing through points B(4,1)B(4,1) and C(3,5)C(3,-5)),
  2. Passing through point A(3,1)A(-3,-1).

Step 1: Calculate the slope of line BC

The slope formula between two points (x1,y1)(x_1, y_1) and (x2,y2)(x_2, y_2) is:

m=y2y1x2x1m = \frac{y_2 - y_1}{x_2 - x_1}

For B(4,1)B(4,1) and C(3,5)C(3,-5): mBC=5134=61=6m_{BC} = \frac{-5 - 1}{3 - 4} = \frac{-6}{-1} = 6

So, the slope of BCBC is 66.


Step 2: Slope of the perpendicular line

The slope of a line perpendicular to another is the negative reciprocal. Therefore:

m=1mBC=16m_{\perp} = -\frac{1}{m_{BC}} = -\frac{1}{6}

The slope of the line perpendicular to BCBC is 16-\frac{1}{6}.


Step 3: Equation of the perpendicular line passing through A

The equation of a line is given by:

yy1=m(xx1)y - y_1 = m(x - x_1)

Here, m=16m = -\frac{1}{6}, and the point is A(3,1)A(-3, -1). Substituting:

y(1)=16(x(3))y - (-1) = -\frac{1}{6}(x - (-3)) y+1=16(x+3)y + 1 = -\frac{1}{6}(x + 3) y+1=16x12y + 1 = -\frac{1}{6}x - \frac{1}{2} y=16x121y = -\frac{1}{6}x - \frac{1}{2} - 1 y=16x32y = -\frac{1}{6}x - \frac{3}{2}


Step 4: Slope and yy-intercept

The slope (mm) of this line is 16-\frac{1}{6}, and the yy-intercept (cc) is 32-\frac{3}{2}.


Step 5: Product of slope and yy-intercept

The product of the slope and yy-intercept is:

mc=(16)(32)m \cdot c = \left(-\frac{1}{6}\right) \cdot \left(-\frac{3}{2}\right) mc=1632=312=14m \cdot c = \frac{1}{6} \cdot \frac{3}{2} = \frac{3}{12} = \frac{1}{4}


Final Answer:

The product of the slope and yy-intercept is:

14\boxed{\frac{1}{4}}


Would you like me to elaborate on any step or explore related problems?

Related Questions:

  1. How do you find the equation of a line perpendicular to a given line?
  2. What is the significance of the negative reciprocal for perpendicular slopes?
  3. How do you find the product of slope and yy-intercept geometrically?
  4. How would the answer change if the perpendicular line passed through a different point?
  5. What is the role of the slope-intercept form in solving such problems?

Tip:

Always confirm the relationship between slopes of perpendicular lines by calculating the product of their slopes (1-1).

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Math Problem Analysis

Mathematical Concepts

Coordinate Geometry
Slopes of Lines
Equation of a Line
Perpendicular Slopes

Formulas

Slope formula: m = (y2 - y1) / (x2 - x1)
Equation of a line: y - y1 = m(x - x1)
Product of perpendicular slopes: m1 * m2 = -1

Theorems

Negative reciprocal relationship of slopes for perpendicular lines

Suitable Grade Level

Grades 9-12