Ответ:
Пошаговое объяснение:
10.
2cos40°cos20° - cos20° = cos(40°-20°)+cos(40°+20°) - cos20° = cos60° = 0,5
2sin40°sin10° + cos50° = cos30° - cos50° + cos50° = cos30° = √3/2
12.
0,5(sin6x-sin2x)-0,5(sin14x-sin2x)=0,5sin6x - 0,5sin14x =
=sin(-4x)cos20x = -sin(4x)cos(20x)
cos5xcosx - cos4xcos2x = 0,5(cos6x+cos4x) - 0,5(cos6x - cos2x) =
=0,5cos4x - 0,5cos2x = -sin(3x)sin(x)
T:42,7=7,4:2,5
t:427/10=74/10:25/10
t:427/10=74/25
t=74/25·10/427
t=69/1000
12 = 2×2×3
18 = 2×3×3
24 = 2×2×2×3
36 = 2×2×3×3
45 = 5×3×3
64 = 2×2×2×2×2×2
1). 2
2). -2
3).0
4).-3
5).12
6).-1
7).23