Coordinate Geometry Review

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Questions and Answers

What is the term for the point where the axes of a Cartesian plane intersect?

  • Origin (correct)
  • Coordinate
  • Intersection
  • Quadrant

The Cartesian plane is divided into how many quadrants?

  • Three
  • Four (correct)
  • Two
  • Eight

What represents the position of a point in the number plane?

  • A linear relation
  • The relation
  • The origin
  • An ordered pair of numbers (correct)

What is a 'relation' defined as in coordinate geometry?

<p>A set of ordered pairs (C)</p> Signup and view all the answers

What is a 'linear relation'?

<p>A relation whose graph is a straight line (D)</p> Signup and view all the answers

How do you find the midpoint of a line segment on a coordinate plane?

<p>Average the x-coordinates and the y-coordinates of the endpoints. (B)</p> Signup and view all the answers

Which theorem is applied to find the distance between two points on a coordinate plane?

<p>Pythagoras' Theorem (D)</p> Signup and view all the answers

What does the gradient of a straight line represent?

<p>The steepness of the line (A)</p> Signup and view all the answers

How is the gradient (m) of a line segment AB defined, given points A(x1, y1) and B(x2, y2)?

<p>$m = (y_2 - y_1) / (x_2 - x_1)$ (A)</p> Signup and view all the answers

If a line slopes upwards from left to right, what can be said about its gradient?

<p>It is positive. (C)</p> Signup and view all the answers

Given $A(x_1, y_1)$ and $B(x_2, y_2)$, which formula correctly calculates the midpoint $P$ of the line segment $AB$?

<p>$P = ((x_1 + x_2)/2, (y_1 + y_2)/2)$ (D)</p> Signup and view all the answers

What is the gradient of a horizontal line?

<p>Zero (D)</p> Signup and view all the answers

What can be said about the gradient of a vertical line?

<p>It is undefined. (D)</p> Signup and view all the answers

If the gradient of a line is $m = tan(\theta)$, and $\theta$ is the angle the line makes with the positive direction of the x-axis, what does $\theta$ represent?

<p>The angle of slope of the line (D)</p> Signup and view all the answers

For a line with a negative gradient, what type of angle does it form with the positive direction of the x-axis?

<p>Obtuse angle (D)</p> Signup and view all the answers

Which of the following is the gradient-intercept form of a straight line equation?

<p>y = mx + c (C)</p> Signup and view all the answers

In the equation y = mx + c, what does 'c' represent?

<p>The y-intercept of the line (B)</p> Signup and view all the answers

What is the 'point-gradient' form of the equation of a straight line, given a point $(x_1, y_1)$ and a gradient $m$?

<p>y - y1 = m(x - x1) (D)</p> Signup and view all the answers

Given the equation of a straight line in intercept form as $x/a + y/b = 1$, what do 'a' and 'b' represent?

<p>a is the x-intercept, b is the y-intercept (A)</p> Signup and view all the answers

How can you determine the equation of a straight line if you know two points on the line?

<p>Use the two points to calculate the gradient, then use the point-gradient form. (B)</p> Signup and view all the answers

What is the general form of the equation of a straight line?

<p>mx + ny + p = 0 (A)</p> Signup and view all the answers

What is the primary method for sketching a straight line given its equation?

<p>Plot and connect any two points on the line. (D)</p> Signup and view all the answers

When two non-vertical lines are parallel, what is true about their gradients?

<p>Their gradients are equal. (B)</p> Signup and view all the answers

If two lines are perpendicular and neither is horizontal or vertical, how are their gradients related?

<p>The product of their gradients is -1. (D)</p> Signup and view all the answers

What is meant by a 'family of straight lines'?

<p>Lines defined by varying a parameter in their equation. (B)</p> Signup and view all the answers

What term describes the variable that, when changed, modifies the characteristics of a family of lines?

<p>Parameter (A)</p> Signup and view all the answers

What does the graphical solution to a system of two simultaneous linear equations represent?

<p>The point of intersection of the two lines (C)</p> Signup and view all the answers

What describes a system of two linear equations that has no solution graphically?

<p>The lines are parallel. (D)</p> Signup and view all the answers

What does it mean if a system of two linear equations has infinitely many solutions?

<p>The lines coincide (are the same). (A)</p> Signup and view all the answers

What condition must be met for two non-vertical lines to be considered parallel?

<p>The lines must have the same gradient. (B)</p> Signup and view all the answers

Given two lines $y = m_1x + c_1$ and $y = m_2x + c_2$, what condition must be met for these lines to be perpendicular, assuming neither line is horizontal or vertical?

<p>$m_1 * m_2 = -1$ (C)</p> Signup and view all the answers

How do you determine if a point $(x, y)$ lies on a given line?

<p>The point's coordinates, when substituted into the equation of the line, satisfy the equation. (C)</p> Signup and view all the answers

To find the tangent of the angle of slope for a line, what information is needed?

<p>The gradient of the line (C)</p> Signup and view all the answers

What is the essential characteristic of the 'general form' of a linear equation?

<p>It can represent all straight lines, including vertical lines. (D)</p> Signup and view all the answers

In modeling real-world scenarios with linear equations, what does the gradient of the line typically represent?

<p>The rate of change or constant factor affecting the variable (B)</p> Signup and view all the answers

The coordinates of point A in the Cartesian plane are (a,b). After the coordinate system is translated such that the origin is now located at (-h,-k), what are the new coordinates of point A?

<p>(a+h, b+k) (A)</p> Signup and view all the answers

A line is defined by the equation $ax + by + c = 0$. If 'a' is very close to zero, and 'b' is significantly larger, what geometric conclusion can most accurately be made about the line?

<p>The line is nearly horizontal. (A)</p> Signup and view all the answers

Flashcards

Number plane

The coordinate plane divided into four regions by two perpendicular axes.

Origin

The point where the axes intersect in the coordinate plane (0,0).

Ordered pair

A pair of numbers (x, y) representing a point's position in the coordinate plane.

Coordinates

The x and y values that define the position of a point in the coordinate plane.

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Relation

A set of ordered pairs (x, y).

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Linear Relation

A relation where the graph is a straight line.

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Midpoint

The point that divides a line segment into two equal parts.

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Distance

The line segment connecting two points.

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Gradient

A measure of the steepness and direction of a line.

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Perpendicular Lines

Lines intersecting at a right angle (90 degrees).

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Parallel lines

Lines that never intersect and have the same slope.

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Angle of slope

The tangent of the angle the line makes with the x-axis.

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Gradient-intercept form

y = mx + c, where m is the gradient and c is the y-intercept.

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Point-gradient form

Knowing the gradient and point we can find our line equation.

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Intercept form

If a line has x-axis intercept a and y-axis intercept b, the equation of the line is x/a + y/b = 1

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Horizontal line

A line parallel to the x-axis = c

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Vertical line

A line parallel to the y-axis, x=a

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General form

An equation of the form mx + ny + p = 0

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Parallel lines

Two non-vertical lines are parallel if they have the same gradient. Conversely, if two non-vertical lines are parallel, then they have the same gradient.

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Perpendicular

Two lines are perpendicular if the product of their gradients is -1

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Parallelism

The slopes of new lines are the same to that of the original

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Parameter.

A variable, often denoted as 'm'. in the equation that defines different lines for example the equation y = mx + 2 can be described to have all non-vertical lines passing through (0, 2)

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Geometry of Simultaneous equations

Having unique, infinite, or no solutions.

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Study Notes

  • Coordinate geometry is reviewed
  • Includes finding midpoints, distances, gradients, slope angles, line equations, and simultaneous equations

Objectives of Coordinate Geometry

  • Find the midpoint of a line segment
  • Find the distance between two points
  • Determine the gradient of a straight line.
  • Calculate the angle of slope of a straight line using its gradient.
  • Use and interpret different forms of a straight line's equation.
  • Determine parallelism and perpendicularity conditions for lines.
  • Use a parameter to represent families of straight lines.
  • Use linear relations to solve problems.
  • Solve and use simultaneous linear equations.

Number Plane (Cartesian Plane)

  • Divided into four quadrants by two perpendicular axes
  • Axes intersect at the origin
  • Points represented by ordered pairs (x, y), called coordinates
  • Using coordinates, one can find straight line equations, distances, and midpoints
  • Coordinate geometry provides foundation for calculus

Relations

  • Defined as ordered pairs (x, y)
  • Relations can be described with a rule relating x and y values, such as y = 2x + 1
  • A relation can be shown graphically on a set of axes
  • A relation that creates a straight line graph is a linear relation

Finding the Midpoint of a Line Segment

  • Special case: segment parallel to an axis aids in getting general result
  • In the general case the coordinates of midpoint P, a line segment AB joining A(x1, y1) and B(x2, y2) are given by:
  • P = ((x₁+x₂)/2, (y₁+y₂)/2)
  • This follows from triangles APC and PBD being congruent (AAS)
  • x coordinate of midpoint will be the average of the x coordinates of the end points
  • y coordinate of midpoint will be the average of the y coordinates of the end points

Finding Distance Between Two Points

  • For points A(x₁, y₁) and B(x₂, y₂), distance found using Pythagoras, by constructing triangle ABC
  • The square of the length of AB = ((x₂ - x₁)² + (y₂ - y₁)²)
  • AB = √((x₂ - x₁)² + (y₂ - y₁)²)

Lines and Gradient

  • Gradient is often defined as "rise over run"
  • Gradient Symbol: m
  • Gradient = rise/run = (y₂ - y₁) / (x₂ - x₁)
  • Order doesn't matter: (y₂ - y₁) / (x₂ - x₁) = (y₁ - y₂) / (x₁ - x₂)
  • Positive gradient -> line slopes upwards from left to right
  • Negative gradient -> line slopes downwards from left to right
  • Horizontal line -> gradient of zero ( m = 0 )
  • Vertical line -> Gradient is undefined

Angle of Slope

  • For positive gradients the line forms an acute angle θ with the x-axis
  • m = tan θ
  • For negative gradients, the line forms an acute angle α with the negative direction of the x-axis, and an obtuse angle θ with the positive x-axis direction. Value of θ will be between 90 and 180 degrees.
  • m = -tan α = tan θ

Equation of a Straight Line

  • Gradient-intercept form: y = mx + c

Vertical lines

  • If horizontal, gradient is 0 and simple y = c, where c is the y-intercept.
  • If vertical then gradient is undefined and x = a, where a is the x-intercept.

A Point and a Gradient

  • Point-gradient form is y - y₁ = m(x - x₁)
  • Given point(x₁, y₁) is located on the line

Two Points

  • Use the formula m = (y₂ - y₁) / (x₂ - x₁)
  • Then use y − y1 = m(x − x₁)

Intercept Form

  • x/a + y/b = 1
  • a and b are the x and y intercepts

General Form

  • Has form mx + ny + p = 0 (m and n not both 0)
  • Describes all straight lines

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