# Math Help - Find the End point

1. ## Find the End point

Hey all,

I've got a question which I'm hoping someone can answer for Me.

if I have the x/y coordinates of the start point of a line (i.e. 0,0),
the angle of the line (i.e. 45 degrees),
and the length of the line (i.e. 10);
how do I calculate the end point of the line?

I'm sure its a pretty basic problem, I just don't have a clue how to go about it.

Sincerely Chryso,

2. In general, if r is the distance from the origin, and $\theta$ is the angle from the positive x-axis, then the endpoint is $(r \cos \theta, r \sin \theta)$.

3. Draw a right triangle and use for example the sine rule.

4. Tan of the angle gives the slope,m

call known point (x1,y1) unknown point is (x,y)

Then slope = rise/run=m = (y1-y)/(x1-x)= m

also length,l is given by sqr root of [(x1-x)^2+(y2-y)^2]=l

you now have a set of simultaneous equations
solve between them