sin4a + sin5a + sin6a = sin4a + sin6a + sin5a, 2sin (5a) * cosa + sin5a = sin5a (2cosa+1)
cos4a + cos5a + cos6a = cos4a + cos6a + cos5a, 2cos5a*cosa + cos5a = cos5a (2cosa+1)
sin5a (2cosa+1) / cos5a (2cosa+1) = sin5a/cos5a = tg5a
30+16√3 = 2 + (21-1)d
<span>d = (28+16√3)/20 = 1,4+0,8√3</span>
12
1/log(8)0,75=log(0,75)8
1/log(3)0,75=log(0,75)6
log(√2)0,5=-2
log(0,75)8-log(0,75)6-2=log(3/4)4/3 -2=-1-2=-3
13
Перейдем к основанию 2
(log(2)7+2)*log(2)32/log(2)∛2=5(log(2)7+2):1/3=15(log(2)7+2)
log(2)7*log(2)8/log(2)(2^1/5)=3log(2)7:1/5=15log(2)7
15(log(2)7+2)-15log(2)7=15log(2)7+30-15log(2)7=30
<span>sin(90*+a)+cos(180*-a)+tg(270*+a)+ctg(360*-a) =cosa-cosa+ctga-ctga=0</span>
Январь - n
февраль - 1,1n
март - 1,2*1,1n = 1,32n
за три месяца = n + 1,1n + 1,32n = 3,42n