Straight Lines

Question 1

How do you find the equation of a perpendicular bisector?

Answer 1

Coordinate - find the midpoint of the two ‘end’ coordinates given

Gradient - find the gradient of the line given by using ‘end’ coordinates then do the ‘-1 thing’ (aka flip+switch) to find the gradient

Then use y-b=m(x-a)

Question 2

What is the midpoint formula?

Answer 2

Between 2 coordinates (x1,y1), (x2,y2)

m= (x1+x2/2, y1+y2/2)

Question 3

What is a median?

Answer 3

A line that goes from one corner of a triangle to the midpoint of the opposite side.

Question 4

What is an altitude?

Answer 4

A line that goes from one corner of a triangle and metre the opposite side at 90*
(i.e. perpendicularly)

Question 5

What is a perpendicular bisector?

Answer 5

A line that crosses another line T the midpoint and at 90*

Question 6

How is a vertical and horizontal line defined?

Answer 6

Vertical lines are x=(x-intercept) and have undefined gradient

Horizontal lines are y=(y-intercept) and have gradient of 0

Everything else is y=mx+c

Question 7

How do you find the equation of an altitude?

Answer 7

Coordinate - use the coordinate of the corner given in question

Gradient - find gradient of perpendicular side met by altitude then ‘flip and switch’ etc.

Then use y-b=m(x-a)

Question 8

How do you find the equation of a median?

Answer 8

Coordinate - use the coordinate of the corner given in question

Find the midpoint of opposite side then find gradient from corner —> midpoint by gradient formula

Then use y-b=m(x-a)