Can someone please tell me how I find the angle from x1,y1 to x2,y2. Thanks in advance, Bluehair

The easiest way is to take the arctan of (y2 - y1)/(x2 - x1) since we know the tangent of the angle = the opposite side divided by the adjacent side.

tan-1((y2 - y1)/(x2 - x1))

That's in radians, so convert to degrees, if that's what you want.

(To convert from radians to degrees, just multiply your answer by 57.3 to get it in degrees)

Answer in degrees:
57.3*(tan-1((y2 - y1)/(x2 - x1))) = angle in degrees

Edited by - BeerNutts on July 3, 2001 12:42:10 PM

Also, check out atan2

Just as an aside, there''s also the question of the angle between (x1,y1) and (x2,y2), the third point (which forms the "center" of the angle) being the Origin. This is quickly calculated at the inverse cosine of the dot product of the two point vectors devided by the product of the vector magnitudes.

ie ang = cos^-1((x1*x2 + y1*y2)/((x1² + y1²)^1/2 * (x2² + y2²)^1/2))

Just for kicks.