straight lines Flashcards
how to find the length of a line if you have the co-ordinates to make the line
create a right angle triangle (using difference in x axis and difference in y axis) then use Pythagoras to find length
how to find the y intercept or x intercept
because it is where it crosses the y axis or x axis you would make the other equal to zero
to find the y intercept you would set x equal to zero
to find the x intercept you would set the y equal to zero
how to stetch any graph
find the x and y axis intercept by setting the other equal to zero
for the y intercept set x=0
for the x intercept set y=0
how to find the co-ordinates where two lines intersect
find the x and y values of where they intersect by writing down both equations and then use the simultaneous equation method to find the x and y values
what is the new equation for a straight line
y-y1=m(x-x1)
where y and x are constant.
but x1 and y1 are coordinates
what two things do we need to find the equation of a line
a gradient
a set of co-ordinates on the line
what if both the numbers top and bottom of a fraction are negative, eg -1/-7 or -2/-8
it would just be the positive version
so 1/7 or 2/8
because think if you are dividing a negative by negative it is always positive.
what is a perpendicular bisector
a line that cuts through another line at the midpoint and at 90 degrees
what would you do when asked to find the co-ordinates of a point but it is in-between (the point connecting) two lines
you would think that if these two lines carried on they would intersect (meet) at that point
so because we want to find out where the two lines meet we would use the simultaneous equation process to find the x and y co-ordinates
what to do in question find the points (a,a) which are a distance of 5 away from the points (0,1)
use the distance of (a,a) and (0,1) by doing Pythagoras and just use (a,a) as if they were normal numbers so height would be (1-a) and width would be (0-a)
then because we are told that the distance is actually 5 between these two points we set the equation we would use to find the distance and just set it equals to 5 then just solve to get a
what to do when asked for the co-ordinates that two lines intersect at
use simultaneous equations to find the x and y co-ordinate
how to prove points are co-linear
same gradient and have a common point
