3)2\/3соsx/7=3
cosx/7=3/2\/3
cosx/7=3\/3/6
cosx/7=\/3/2
x/7=+-π/6+2πn n€Z
x=+-7π/6+2πn n€Z
4)7+7×3=28
3)2\/3соsx/7=3
cosx/7=3/2\/3
cosx/7=3\/3/6
cosx/7=\/3/2
x/7=+-π/6+2πn n€Z
x=+-7π/6+2πn n€Z
4)7+7×3=28