Sin 2x = 2 sin x cos x
sin (pi -x) = sin x
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cos(pi/33)*cos(2pi/33)*cos(4pi/33)*cos(8pi/33)*cos(16pi/33) = sin(pi/33)*cos(pi/33)*cos(2pi/33)*cos(4pi/33)*cos(8pi/33)*cos(16pi/33) / sin(pi/33) = sin(2pi/33)*cos(2pi/33)*cos(4pi/33)*cos(8pi/33)*cos(16pi/33) / 2sin(pi/33) = sin(4pi/33)*cos(4pi/33)*cos(8pi/33)*cos(16pi/33) / 4sin(pi/33) = sin(8pi/33)*cos(8pi/33)*cos(16pi/33)/ 8sin(pi/33) = sin(16pi/33)*cos(16pi/33)/ 16sin(pi/33) = sin(32pi/33) / 32pi(33) = sin(pi-pi/33)/16sin(pi/33) = sin(pi/33) / 32sin(pi/33) = 1/32
2) =20а^5-5а^4+5а^2
3) =6с^2-17сх+5х^2
4) =9а^2+12ав+4в^2
A2=0,4
a9=3,9
a9=a4+5d
3,9=0,4+5d
5d=3,5
d=3,5/5
d=0,7
Ответ: d=0,7.