Math Problem Statement

What is the slope of these lines and are they parallel, perpendicular, or intersecting? Line 1: (15, 20) and (17, 18); Line 2: (-22, -18) and (-20, -16).

Solution

Let's solve the problem step by step.

We need to find the slopes of the two lines and then determine their relationship (parallel, perpendicular, or intersecting). The slope formula for a line through 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}

Line 1: Points (15, 20) and (17, 18)

The slope m1m_1 of Line 1 is:

m1=18201715=22=1m_1 = \frac{18 - 20}{17 - 15} = \frac{-2}{2} = -1

Line 2: Points (-22, -18) and (-20, -16)

The slope m2m_2 of Line 2 is:

m2=16(18)20(22)=16+1820+22=22=1m_2 = \frac{-16 - (-18)}{-20 - (-22)} = \frac{-16 + 18}{-20 + 22} = \frac{2}{2} = 1

Relationship between the lines

  • If the slopes are equal, the lines are parallel.
  • If the product of the slopes is 1-1, the lines are perpendicular.
  • Otherwise, they are intersecting.

For Line 1, m1=1m_1 = -1, and for Line 2, m2=1m_2 = 1. The product of the slopes is:

m1×m2=1×1=1m_1 \times m_2 = -1 \times 1 = -1

Since the product is 1-1, the lines are perpendicular.


Would you like more details or have any questions? Here are some related questions to explore further:

  1. What is the equation of Line 1 in slope-intercept form?
  2. What is the equation of Line 2 in slope-intercept form?
  3. How do you find the point of intersection between two lines?
  4. Can two perpendicular lines ever be parallel?
  5. What is the significance of the negative reciprocal in determining perpendicularity?

Tip: Perpendicular lines have slopes that are negative reciprocals of each other.

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Math Problem Analysis

Mathematical Concepts

Geometry
Linear Equations
Slopes of Lines

Formulas

Slope formula: m = (y2 - y1) / (x2 - x1)
Conditions for parallel lines: equal slopes
Conditions for perpendicular lines: product of slopes equals -1

Theorems

Slopes of parallel and perpendicular lines

Suitable Grade Level

Grades 9-12