Would someone be so kind as to help me with a math equation?

From: Dark Alchemist (GhostOfACPast_at_gmail.com)
Date: 01/01/05 

Date: 31 Dec 2004 17:05:10 -0800

I am trying to convert a sin into a cos but all I could come up with
was the half angle formula which does not give me any negatives. The
half angle formula has the correct number but it loses the sign.

Formula I tried (simplified) was

x=sin(angle)
y = sqrt(1 - x^2)

At first I thought I had it because of this

....Sin.........Cos......Results from the formula above
-0.95297934 -0.30303527 0.30303528
-0.95486454 -0.29704159 0.2970416
-0.95671205 -0.29103617 0.29103617
-0.95852179 -0.28501927 0.28501926
-0.96029369 -0.27899111 0.27899109
-0.96202767 -0.27295194 0.27295194
-0.96372368 -0.26690199 0.26690199
-0.96538164 -0.26084151 0.2608415
-0.96700149 -0.25477073 0.25477072

but when I tested it more I found this

....Sin.........Cos......Results from the formula above
0.05024432 -0.99873696 0.99873696
0.04396812 -0.99903293 0.99903293
0.03769018 -0.99928947 0.99928947
0.03141077 -0.99950656 0.99950656
0.0251301 -0.99968419 0.99968419
0.01884845 -0.99982235 0.99982235
0.01256604 -0.99992104 0.99992104
0.00628315 -0.99998026 0.99998026

Notice the digits are correct (within the tolerance of the program I
used) but I lost their sign. Now the only numbers I know or can
manipulate is x after the sinewave has been created.

Is there a formula for a full angle as there is for a half angle?
Thank you.

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