Re: [Flashcoders] Q:Elementary Trig part 2
On 10/22/06, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote: Another way of stating my problem: Given an initial angle, and a circle with radius r, how do you determine the x,y coordinates of the point p1 on the circumference of this circle...assuming the circle's center is at 0,0.? Just use the code I posted in reply to "Elementary Trig" (part 1). It works for any angle, not just 120 and 240 degrees. Your "initial angle" needs to be between (the vector) p1 and something. That something is often (1, 0) -- one unit along the X axis. So, use that for x1, y1 in the code I posted, and your vector will be (x2, y2), or put differently, (Math.cos( initialAngle ), -Math.sin( initialAngle )) if initialAngle is the angle between your initial point and the X axis. However, it's only one unit (one pixel) from the center, not the radius r. You still need to scale it, simply multiply x and y by r. In short: x = Math.cos( angle ) * r; y = -Math.sin( angle ) * r; HTH, Mark ___ Flashcoders@chattyfig.figleaf.com To change your subscription options or search the archive: http://chattyfig.figleaf.com/mailman/listinfo/flashcoders Brought to you by Fig Leaf Software Premier Authorized Adobe Consulting and Training http://www.figleaf.com http://training.figleaf.com
RE: [Flashcoders] Q:Elementary Trig part 2
Ah well.. indeed -- point is still made the same in the end I gather. Looks like he got what he needed. > -Original Message- > From: [EMAIL PROTECTED] [mailto:flashcoders- > [EMAIL PROTECTED] On Behalf Of Pete Miller > Sent: Sunday, October 22, 2006 11:52 PM > To: Flashcoders mailing list > Subject: RE: [Flashcoders] Q:Elementary Trig part 2 > > Check your algebra, > > Since sin(a) = y/r, then y = r sin(a), etc. > > P. ___ Flashcoders@chattyfig.figleaf.com To change your subscription options or search the archive: http://chattyfig.figleaf.com/mailman/listinfo/flashcoders Brought to you by Fig Leaf Software Premier Authorized Adobe Consulting and Training http://www.figleaf.com http://training.figleaf.com
RE: [Flashcoders] Q:Elementary Trig part 2
Check your algebra, Since sin(a) = y/r, then y = r sin(a), etc. P. >> -Original Message- >> From: [EMAIL PROTECTED] [mailto:flashcoders- >> [EMAIL PROTECTED] On Behalf Of Jayson K Hanes >> Sent: Sunday, October 22, 2006 7:42 PM >> To: Flashcoders mailing list >> Subject: RE: [Flashcoders] Q:Elementary Trig part 2 >> >> Been awhile since I've explained this to anyone.. lets see how this >> goes! >> >> "SOHCAHTOA" (so-ca-toa) >> >> Sin(a) = opposite/hypotenuse >> Cos(a) = adjacent/hypotenuse >> Tan(a) = opposite/adjacent >> >> a = angle in RADIANS *not* degrees.. you'll have to convert degrees to >> radians with knowing: >> >> ..there are PI (3.14159..) radians in 180 degrees (a fundamental), thus: >> a = A*(PI/180), thus: >> a = 45*(3.14159/180) = .785 (roughly) >> >> Given r and angle=A degrees converted to a radians, r is the same as the >> length of a basic triangles' hypotenuse in this -- we're looking for x,y >> .. moving on: >> >> A=45 degrees but converted to a=.785 radians (approx).. we know that: >> >> r=10, and should know that: >> r=sqrt(x^2+y^2) (per Pythagoras theorem) >> >> so we're going to reverse format the SOH and CAH parts since we know the >> length of the hypotenuse and need to find out x and y (the opposite and >> adjacent sides' lengths) one at a time based on angle, a in radians: >> >> sin(a)=y/r, and, >> cos(a)=x/r, which translates to: >> >> y=sin(a)/r, and >> x=cos(a)/r, however: >> >> y=sin(a)/10, and >> x=cos(a)/10, thus: >> >> y=sin(.785)/10, and >> x=cos(.785)/10, thus: >> >> y=0.707/10 = 7.07 (roughly) >> x=0.707/10 = 7.07 (roughly) >> >> I think that should set you on you on track! Hope that helps :) >> >> -Jayson >> >> > -Original Message- >> > From: [EMAIL PROTECTED] [mailto:flashcoders- >> > [EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] >> > Sent: Sunday, October 22, 2006 3:11 PM >> > To: flashcoders@chattyfig.figleaf.com >> > Subject: [Flashcoders] Q:Elementary Trig part 2 >> > >> > Another way of stating my problem: >> > >> > >> > Given an initial angle, and a circle with radius r, how do you >> determine >> > the x,y coordinates of the point p1 on the circumference of this >> > circle...assuming the circle's center is at 0,0.? >> > >> > >> > >> > [e] jbach at bitstream.ca >> > [c] 416.668.0034 >> > [w] www.bitstream.ca >> ___ >> Flashcoders@chattyfig.figleaf.com >> To change your subscription options or search the archive: >> http://chattyfig.figleaf.com/mailman/listinfo/flashcoders >> >> Brought to you by Fig Leaf Software >> Premier Authorized Adobe Consulting and Training >> http://www.figleaf.com >> http://training.figleaf.com ___ Flashcoders@chattyfig.figleaf.com To change your subscription options or search the archive: http://chattyfig.figleaf.com/mailman/listinfo/flashcoders Brought to you by Fig Leaf Software Premier Authorized Adobe Consulting and Training http://www.figleaf.com http://training.figleaf.com
RE: [Flashcoders] Q:Elementary Trig part 2
Been awhile since I've explained this to anyone.. lets see how this goes! "SOHCAHTOA" (so-ca-toa) Sin(a) = opposite/hypotenuse Cos(a) = adjacent/hypotenuse Tan(a) = opposite/adjacent a = angle in RADIANS *not* degrees.. you'll have to convert degrees to radians with knowing: ..there are PI (3.14159..) radians in 180 degrees (a fundamental), thus: a = A*(PI/180), thus: a = 45*(3.14159/180) = .785 (roughly) Given r and angle=A degrees converted to a radians, r is the same as the length of a basic triangles' hypotenuse in this -- we're looking for x,y .. moving on: A=45 degrees but converted to a=.785 radians (approx).. we know that: r=10, and should know that: r=sqrt(x^2+y^2) (per Pythagoras theorem) so we're going to reverse format the SOH and CAH parts since we know the length of the hypotenuse and need to find out x and y (the opposite and adjacent sides' lengths) one at a time based on angle, a in radians: sin(a)=y/r, and, cos(a)=x/r, which translates to: y=sin(a)/r, and x=cos(a)/r, however: y=sin(a)/10, and x=cos(a)/10, thus: y=sin(.785)/10, and x=cos(.785)/10, thus: y=0.707/10 = 7.07 (roughly) x=0.707/10 = 7.07 (roughly) I think that should set you on you on track! Hope that helps :) -Jayson > -Original Message- > From: [EMAIL PROTECTED] [mailto:flashcoders- > [EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] > Sent: Sunday, October 22, 2006 3:11 PM > To: flashcoders@chattyfig.figleaf.com > Subject: [Flashcoders] Q:Elementary Trig part 2 > > Another way of stating my problem: > > > Given an initial angle, and a circle with radius r, how do you determine > the x,y coordinates of the point p1 on the circumference of this > circle...assuming the circle's center is at 0,0.? > > > > [e] jbach at bitstream.ca > [c] 416.668.0034 > [w] www.bitstream.ca ___ Flashcoders@chattyfig.figleaf.com To change your subscription options or search the archive: http://chattyfig.figleaf.com/mailman/listinfo/flashcoders Brought to you by Fig Leaf Software Premier Authorized Adobe Consulting and Training http://www.figleaf.com http://training.figleaf.com
