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Lesson 4-4: Coordinate Geometry Basics

Scenario: Navigation & Mapping - Learn coordinate geometry through GPS navigation and map reading!

Duration: 60-75 minutesScenario: Navigation & Mapping

Learning Objectives

  • Plot and identify points on a coordinate plane
  • Calculate distances between points
  • Find midpoints of line segments
  • Apply coordinate geometry to navigation problems

Navigation Scenario

The Problem

You're using a GPS navigation system to plan a trip. You need to find the distance between two cities and determine the midpoint for a rest stop. The cities are located at coordinates A(3, 4) and B(7, 8).

Navigation Challenge:
Find the distance between cities A(3, 4) and B(7, 8), and locate the midpoint for a rest stop.

Coordinate Plane

Y
X
0
A(3,4)
B(7,8)

Coordinate plane showing points A and B

Coordinate System Basics

Understanding Coordinates

Coordinate Format: (x, y) where x is horizontal position and y is vertical position

  • • Origin (0, 0) is at the center
  • • X-axis: horizontal line (left-right)
  • • Y-axis: vertical line (up-down)
  • • Quadrants: I, II, III, IV (counterclockwise from top-right)

Quadrants

Quadrant I

(+, +) - Top right
Example: (3, 4)

Quadrant II

(-, +) - Top left
Example: (-3, 4)

Quadrant III

(-, -) - Bottom left
Example: (-3, -4)

Quadrant IV

(+, -) - Bottom right
Example: (3, -4)

Distance Formula

The Formula

Distance Formula: d = √[(x₂ - x₁)² + (y₂ - y₁)²]

This formula comes from the Pythagorean theorem applied to the coordinate plane.

Solving the Navigation Problem

Given: A(3, 4) and B(7, 8)

Step 1: Find differences

x₂ - x₁ = 7 - 3 = 4
y₂ - y₁ = 8 - 4 = 4

Step 2: Apply distance formula

d = √(4² + 4²) = √(16 + 16) = √32 ≈ 5.66 units

Midpoint Formula

The Formula

Midpoint Formula: M = ((x₁ + x₂)/2, (y₁ + y₂)/2)

The midpoint is exactly halfway between two points.

Finding the Rest Stop Location

Given: A(3, 4) and B(7, 8)

Step 1: Calculate x-coordinate

x = (3 + 7)/2 = 10/2 = 5

Step 2: Calculate y-coordinate

y = (4 + 8)/2 = 12/2 = 6

Answer: Rest stop should be at M(5, 6)

Practice Problems

Problem 1: Distance

Find the distance between points P(1, 2) and Q(5, 6).

Your solution:

Problem 2: Midpoint

Find the midpoint between R(-2, 3) and S(4, -1).

Your solution:

Problem 3: Navigation Application

A delivery truck needs to go from warehouse A(0, 0) to store B(8, 6). Find the distance and midpoint for a fuel stop.

Your calculation: