# Straight Line Flashcards

1
Q

Lines with equal gradient are…

A

Parallel

2
Q

What is the gradient of a horizontal line

A

m = 0

3
Q

What is the gradient of a vertical line?

A

m is undefined

4
Q

What is the gradient formula?

A
5
Q

A line with zero gradient is…

A

Horizontal (parallel to the x axis)

6
Q

Parallel lines have…

A

7
Q

How do you find the equation of a straight line?

A
1. Find the gradient
2. Need to know a point on the line (a, b)
3. Sub into y - b = m( x - a )
8
Q

How do you find the mid point of a line?

A
9
Q

What is the rule for perpendicular lines?

A
10
Q

What is the distance formula?

A
11
Q

What is a median of a triangle?

A

Median is a line drawn from one vertex to the midpoint of the opposite side

12
Q

What is an altitude of a triangle?

A

Altitude is a line through a vertex, perpendicular to the
opposite side.

13
Q

What is a perpendicular bisector?

A

A line which bisects (cuts in half) a given line at right-angles

14
Q

How do you find the equation of a median
through a point of a triangle?

A
1. Draw a sketch
2. Find the midpoint required
3. Find the gradient from the vertex to the midpoint
4. Use y – b = m( x – a )
15
Q

How do you find the equation of an altitude of a triangle through side BC?

A
1. Draw a sketch
2. Find the gradient of BC
3. Use m1 x m2 = -1 to find
gradient of the altitude
4. Use y – b = m (x – a)
16
Q

How do you find the equation of a perpendicular bisector?

A
1. Draw a sketch
2. Find midpoint of AB
3. Find gradient of AB
4. Use m1 x m2 = -1 to find gradient of perpendicular bisector CD
5. Use y – b = (m – a )
17
Q

How do you know if a point lies on a line or curve?

A

Substitute the x and y coordinates of the point into the equation of the line or curve. If the L side = R side, then the point does lie on the line.

18
Q

How do you know 3 lines are concurrent?

A

For three lines to be concurrent, they must all pass through a single point.
___________________________

Find where 2 lines intersect and sub x and y into 3rd. If Left = Right, then lines are concurrent

19
Q

How do you find the size of the angle between a line and the x-axis?

A
20
Q

How do you show that the points A, B and C are collinear?

A
1. Show that mAB = mBC
2. State that the two line segments AB and BC have a common point B
21
Q

What does it mean if three points are said to be collinear?

A

The lie on the same straight line and share a common point

22
Q

What is the equation of this line?

A

x = -2

23
Q

What is the equation of this line?

A

y = 4

24
Q

How to you find the gradient of a line in the general form Ax + By + C = 0

A

Rearrange into y = mx + c

25
Q

How to you find the point where a line cuts the x axis?

A

Set y = 0

26
Q

How do you find the point where a line cuts the y axis?

A

Set x = 0

27
Q

How to you find the point where two lines intersect?

A

Use simultaneous equations