locus cheat sheet (1 Viewer)

[bob fossil]

i have to make a cheat sheet on locus problems.


Can someone list all of them and how to solve them.
like P is equidistant to point a and point b

 

[Divided_By_Zero]

Well let P = (x,y)

And now do the distance formula of PA and make it equal to PB

Now square both sides to get rid of the square root signs and bring it all to one side for general equation of a straight line.

For a Locus of P when PA is double the distance of PB ( PA=2PB) when you square the sides make sure you square the 2 (PA^2=4PB^2)

For locus of P if it is always r units from a point (h,k) it will be a circle with midpoint (h,k) and radius r eg. (x-h)^2+(x-k)^2=r^2

and i'm too lazy to do more for now

 

[Iruka]

To do well at locus questions mostly you need to know all your coordinate geometry formulas.

Some basic plane geometry probably helps, too (circle geo, properties of quadrilaterals, stuff like that).

 

[khorne]

Last time I checked, we didn't do your homework for you =]

 

[bob fossil]

Last time I checked, we didn't do your homework for you =]

Keep it up=]

 

[khorne]

Ok...so you understand nothing...

See more people would be ready to help if you presented them with several (maybe 3 or so) problems, and asked for help, showing what thought you have done so far, and attempted solutions.

 

[bob fossil]

Ok...so you understand nothing...

See more people would be ready to help if you presented them with several (maybe 3 or so) problems, and asked for help, showing what thought you have done so far, and attempted solutions.

I just wanted to know how to do the 4 types of locus questions that can be asked in a 2 unit exam at this stage of year 12 for my cheat sheet?

 

[ItsColinoOo0o]

dont you just derive it all?
find derivative
sub in x value
find gradient
use
y-y1=m(x-x1)

oh and if you are talking about
formulars like
xx0=2a(y-y0) for chord of contact and etc

its in the cambridge book some wehre

 

[bob fossil]

Thanks to the people that helped.

And for the person that asked I needed:

2 points in fixed ratio to make a circle.
equidistant from 2 points.
equidistant from a point and a line.
equidistant from 2 non parrallel lines.

Thanks again buddy

 

[TheStallion]

Opening a textbook would be a much easier way to learn this, but equidistant from 2 points - just make two distance formulas equal to each other. Expand and put into general form.