Question

решить уравнение   ctg 2х+4=0      cos3х= -1/2

Answer 1

ctg2x+4=0
2x+4=arcctg0+Pn
2x+4=p/2+pn
2x=p/2-4+pn
x=p/4-2+pn
cos3x=-1/2
3x=+-arccos-1/2+2pn
3x=+-p-arccos1/2+2pn
3x=+-2p/3+2pn
x=+-2p/6+2pn/3
x=+-p/3+2pn/3