mmb1

Verified answer

cos 2x= 2cos^2 x -1 = 2(3/5)^2 -1 = 18/25 - 1= - 7/25 
cos (arccos x)=x
sin 2x=2sinxcosx= 2 * 12/13* 5/13 = 120/169
sin (arrcos x) = √(1-x^2)
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tg x = 1/ctg x
tg (x-y)= (tgx - tgy)/(1 +tgx * tgy)=(3-1/3)/(1+3*1/3)=4/3
tg (x+y)= (tgx + tgy)/(1 -tgx * tgy) = (2+1/2)/(1-2*1/2)=5/2 / 0 неопределен