sin10sin30sin50sin70=cos10sin10sin30sin50sin70/cos10=
=1/2sin20sin70sin30sin50/cos10=1/4sin40sin50sin30/cos10=
=1/8sin80sin30/cos10=1/8cos10sin30/cos10=
=1/8sin30=1/8*1/2=1/16=0.0625
или
sin10sin30sin50sin70=1/2sin10sin50sin70=
=1/4(cos40-cos60 )sin70=1/4(cos40-0.5)sin70=
=1/4cos40sin70-1/8sin70=1/8(sin110+sin30)-1/8sin70=
=1/8sin110+1/16-1/8sin70=1/8sin(180-70)+1/16-1/8sin70=
=1/8sin70+1/16-1/8sin70=1/16=0.0625
Y = 0,5x-3
а) При х = 4
у = 0,5*4 - 3 = 1
б) При у = 5
0,5х-3 = 5
0,5х = 8
х = 16
Ответ : 1; 16
4X+4-X=5
4X-X=5-4
3X=1X=1/3
вроде так