## Re:Math help!!

##### Quote

Andrew Rossmann wrote in message <360693E4.C637CDF3@no_junk.ntsource.com>...

> I'm trying to draw some arcs. I know the 'direction' (CW or CCW),

>start point, end point, and either the radius or centerpoint. I need to

>convert that to either centerpoint and angle, or three points on the

I don't have time to work out the details for you, but perhaps this will

get you started.

If I understand you correctly you have two points A and B on the circle

and the center point, C.

You can use the arctan2 function to get the angle between a radius line

and the X-axis (if I remember correctly). So something like

arctan2(Ay-Cy, Ax-Cx) should give you the angle from the X-axis to

point A and arctan2(By-Cy, Bx-Cx) should give you the angle from

the X-axis to the point B. Draw your arc by creating intermediate

points. These intermediate points will be something like

(Cx + R*COS(theta), Cy+R*SIN(theta)).

I you need an arctan2 function, look on the Delphi Math Functions

pages in my Computer Lab.

I hope I didn't trade haste for accuracy in this reply.

efg

_________________________________________

efg's Computer Lab: http://infomaster.net/external/efg

Earl F. Glynn E-Mail: EarlGl...@att.net

Overland Park, KS USA