Finding the Slope of the Line Passing Through A and B

Oct 13, 2025 by wbrum.org 104 views

Introduction

In geometry, an altitude of a triangle is a line segment through a vertex and perpendicular to the opposite side. Given the vertices of a triangle, we can find the equation of the altitude from a specific vertex. In this article, we will focus on finding the equation of the altitude from vertex C of triangle ABC, given the coordinates of vertices A, B, and C.

Understanding the Problem

To find the equation of the altitude from vertex C, we need to understand the concept of slope and perpendicular lines. The slope of a line is a measure of how steep it is, and two lines are perpendicular if their slopes are negative reciprocals of each other. In this case, we need to find the slope of the line passing through vertices A and B, and then find the slope of the altitude from vertex C, which is perpendicular to the line passing through A and B.

Finding the Slope of the Line Passing Through A and B

The slope of the line passing through two points (x1, y1) and (x2, y2) is given by the formula:

m = (y2 - y1) / (x2 - x1)

Using this formula, we can find the slope of the line passing through vertices A(3, 1) and B(5, -2):

m = (-2 - 1) / (5 - 3) = -3 / 2 = -1.5

Finding the Slope of the Altitude from Vertex C

Since the altitude from vertex C is perpendicular to the line passing through A and B, its slope is the negative reciprocal of the slope of the line passing through A and B. The negative reciprocal of -1.5 is 2/3.

Finding the Equation of the Altitude from Vertex C

Now that we have the slope of the altitude from vertex C, we can use the point-slope form of a line to find its equation. The point-slope form of a line is given by:

y - y1 = m(x - x1)

where (x1, y1) is a point on the line, and m is the slope. We can use vertex C(7, 4) as the point on the line, and 2/3 as the slope:

y - 4 = (2/3)(x - 7)

To simplify the equation, we can multiply both sides by 3 to eliminate the fraction:

3(y - 4) = 2(x - 7) 3y - 12 = 2x - 14

Now, we can add 12 to both sides and subtract 2x from both sides to get the equation in the standard form:

2x - 3y = -14 + 12 2x - 3y = -2

Conclusion

In this article, we found the equation of the altitude from vertex C of triangle ABC, given the coordinates of vertices A, B, and C. We first found the slope of the line passing through vertices A and B, and then found the slope of the altitude from vertex C, which is perpendicular to the line passing through A and B. Finally, we used the point-slope form of a line to find the equation of the altitude from vertex C.

Example Use Case

The equation of the altitude from vertex C can be used to find the coordinates of the point where the altitude intersects the opposite side of the triangle. This can be useful in a variety of applications, such as finding the area of the triangle or the length of the altitude.

Step-by-Step Solution

Here is a step-by-step solution to the problem:

Find the slope of the line passing through vertices A and B: m = (-2 - 1) / (5 - 3) = -3 / 2 = -1.5
Find the slope of the altitude from vertex C: m = -1 / (-1.5) = 2/3
Use the point-slope form of a line to find the equation of the altitude from vertex C: y - 4 = (2/3)(x - 7)
Simplify the equation: 3(y - 4) = 2(x - 7) 3y - 12 = 2x - 14 2x - 3y = -14 + 12 2x - 3y = -2

Frequently Asked Questions

What is the equation of the altitude from vertex C of triangle ABC? The equation of the altitude from vertex C is 2x - 3y = -2.
How do I find the equation of the altitude from a vertex of a triangle? To find the equation of the altitude from a vertex of a triangle, you need to find the slope of the line passing through the vertex and the opposite side, and then use the point-slope form of a line to find the equation of the altitude.
What is the slope of the altitude from vertex C? The slope of the altitude from vertex C is 2/3.

Introduction

In our previous article, we discussed how to find the equation of the altitude from vertex C of triangle ABC, given the coordinates of vertices A, B, and C. In this article, we will provide a Q&A section to help clarify any doubts and provide additional information on the topic.

Q&A

Q: What is the equation of the altitude from vertex C of triangle ABC?

A: The equation of the altitude from vertex C of triangle ABC is 2x - 3y = -2.

Q: How do I find the equation of the altitude from a vertex of a triangle?

A: To find the equation of the altitude from a vertex of a triangle, you need to follow these steps:

Find the slope of the line passing through the vertex and the opposite side.
Find the slope of the altitude from the vertex, which is the negative reciprocal of the slope of the line passing through the vertex and the opposite side.
Use the point-slope form of a line to find the equation of the altitude from the vertex.

Q: What is the slope of the altitude from vertex C?

A: The slope of the altitude from vertex C is 2/3.

Q: How do I find the slope of the line passing through two points?

A: To find the slope of the line passing through two points (x1, y1) and (x2, y2), you can use the formula:

m = (y2 - y1) / (x2 - x1)

Q: What is the point-slope form of a line?

A: The point-slope form of a line is given by:

y - y1 = m(x - x1)

where (x1, y1) is a point on the line, and m is the slope.

Q: How do I simplify the equation of the altitude from vertex C?

A: To simplify the equation of the altitude from vertex C, you can multiply both sides of the equation by 3 to eliminate the fraction:

3(y - 4) = 2(x - 7) 3y - 12 = 2x - 14

Then, you can add 12 to both sides and subtract 2x from both sides to get the equation in the standard form:

2x - 3y = -14 + 12 2x - 3y = -2

Q: What is the standard form of a line?

A: The standard form of a line is given by:

Ax + By = C

where A, B, and C are constants.

Q: How do I find the coordinates of the point where the altitude intersects the opposite side of the triangle?

A: To find the coordinates of the point where the altitude intersects the opposite side of the triangle, you can substitute the equation of the altitude into the equation of the opposite side and solve for the x-coordinate. Then, you can substitute the x-coordinate into the equation of the altitude to find the y-coordinate.

Q: What are some real-world applications of finding the equation of the altitude from a vertex of a triangle?

A: Some real-world applications of finding the equation of the altitude from a vertex of a triangle include:

Finding the area of a triangle
Finding the length of the altitude
Finding the coordinates of the point where the altitude intersects the opposite side of the triangle
Designing buildings and bridges
Creating computer-aided designs (CAD) of buildings and bridges