Как то так,надеюсь все цифры понятны)
26.
-3ctg(360°-α)-2tg(90°-α)=-3*(-ctgα)-2ctgα=3ctgα-2ctgα=ctgα
0.15
Ответ: 0,15
27. <u>12tg(4π/7) </u>= <u>12tg(8π/14) </u>= <u>12tg(7π/14 + π/14) </u>=
ctg(π/14) ctg(π/14) ctg(π/14)
= <u>12tg(π/2 + π/14) </u>= <u>-12ctg(π/14) </u>= -12
ctg(π/14) ctg(π/14)
Ответ: -12
Log245+log=log(245*)=log49=log7²=2
Решение
<span>x</span>²<span>-16x+48 = 0
(x</span>² - 16x + 64) - 64 + 48 = 0
(x - 8)² - 16 = 0
(x - 8)² = 16
x - 8 = 4 или x - 8 = - 4
x₁ = 12 x₂ = 4
Ответ: x₁ = 12; x₂ = 4
1-sin²(x/2-3π)-cos²(x/4)+sin²(x/4)=(1-sin²(x/2-3π))-(cos²(x/4)-sin²(x/4))=
=cos²(x/2-3π)-cos(2*(x/4))=(cos(3π-x/2))²-cos(x/2)=(-cos(x/2))²-cos(x/2)=cos²(x/2)-cos(x/2)