> Peter Proost wrote:
>> I've got a line going from x1,y1 to x2,y2 then the user inputs an
>> angle and a length for a second line starting from x2,y2 going to
>> x3,y3 But how do I calculate the value for x3,y3? I think I need to do
>> something with cosinus and sinus and my angle and length but I don't
>> know what.
>
> x3=x2+r*cos(t)
> y3=y2+r*sin(t)
>
> where r is the length (commonly referred to as the radius in this situation)
> and t is the angle in radians (theta, angles are usually called theta for
> these things).
>
> (angle in radians)=(angle in degrees)*pi/180
>
> And don't forget that the screen y-axis is upside-down compared to what
> you'd draw with pencil and paper.
>

> Peter Proost wrote:
>> I've got an extra question which I forgot to mention in my original
>> post. Thanks to your answer I can calculate x3,y3, but they need to be
>> calculated with respect to the angle of the x1,y1 - x2,y2 line. I hope
>> you get what I mean.
>
> Angle of line (p1,p2) in radians=atan2(y2-y1, x2-x1) where p1=(x1,y1) and
> p2=(x2,y2).
>
> I recommend that you keep all angles in the code in radians, and only do the
> degrees<->radians conversions at the user-interface level.
>
> HTH
>