T=2π*1/3=2ππ/3
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X)-12=10 y)15=-18 20=-24
-9=7,5
-6=5
0=0
3=-2,5
6=-5
y)40=-48
1. (1 - cos^2t / 1-sin^2t) + tgt*ctgt = 1 / cos^2t
sin^2t / cos^2t + 1 = (sin^2t + cos^2t) / cos^2t = 1 / cos^2t
1/cos^2t = 1/cos^2t
2. sint = -15/17
cos^2t = 1 - sin^2t = 1 - 225/289 = 64/289
cost = -8/17
tgt = sint/cost
tgt = 15*17/17*8 = 15/8
ctgt = 1/tgt = 8/15