Sin(10cosx)=-1
10cosx=-pi/2+2pik, k∈z
cosx=-pi/20+pi/5k, k∈z
-pi/20+pi/5k ∈ [-1;1]
pi/5k ∈ [-1+pi/20; 1+pi/20]
k ∈ [-5/pi+0,25; 5/pi+0,25] <=> k={-1;0;1}
cosx=-pi/4<=>х=+-arccos(-pi/4)+2pin, n∈z
cosx=-pi/20<=>x=+-arccos(-pi/20)+2pin, n∈z
cosx=3pi/20<=>x=+-arccos(3pi/20)+2pin, n∈z