у=1-cosx

-1<=cos x<=1

-1<=-cos x<=1

0<=1-cos x<=2

[0;2]

у=1-cos2x.

-1<=cos 2x<=1

-1<=-cos 2x<=1

0<=1-cos 2x<=2

[0;2]

у=1/2 sinx cos x=1/4 sin 2x

-1<=sin2x<=1

-1/4<=1/4sin2x<=1/4

[-1/4;1/4]

найти область определения функции:4)у=tg 5x

5x не равно pi/2+pi*k

x   не равно pi/10+pi\5*k

(pi\10+pi/5*k;3*pi/10*k+pi\5)