![sin(-{5\pi\over2}+x)=-cosx\\\sqrt2cosxsinx=cosx\\\\cosx=0\\sinx={1\over\sqrt2}\\\\x={\pi\over2}+\pi k, k\in \mathbb {Z}\\x=(-1)^k{\pi\over4}+\pi k, k\in \mathbb {Z}](https://tex.z-dn.net/?f=sin%28-%7B5%5Cpi%5Cover2%7D%2Bx%29%3D-cosx%5C%5C%5Csqrt2cosxsinx%3Dcosx%5C%5C%5C%5Ccosx%3D0%5C%5Csinx%3D%7B1%5Cover%5Csqrt2%7D%5C%5C%5C%5Cx%3D%7B%5Cpi%5Cover2%7D%2B%5Cpi+k%2C+k%5Cin+%5Cmathbb+%7BZ%7D%5C%5Cx%3D%28-1%29%5Ek%7B%5Cpi%5Cover4%7D%2B%5Cpi+k%2C+k%5Cin+%5Cmathbb+%7BZ%7D)
Корни на отрезке <span>[(9пи)/2; 6пи]:
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![x\in\{{9\pi\over2};{19\pi\over4};{11\pi\over2}\}](https://tex.z-dn.net/?f=x%5Cin%5C%7B%7B9%5Cpi%5Cover2%7D%3B%7B19%5Cpi%5Cover4%7D%3B%7B11%5Cpi%5Cover2%7D%5C%7D)
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Одна сторона увеличилась в 4 корень из двух
<span>Тогда периметр станет 16 корней из 2 а</span>
cosx + 3 sinx = 2
cosx = 2 - 3 sinx
(cosx)^2 = (2 - 3 sinx)^2
(cosx)^2 = 4 - 12sinx + 9(sinx)^2
1 - (sinx)^2 = 9(sinx)^2 - 12sinx + 4
10(sinx)^2 - 12sinx + 3 = 0
(sinx)^2 - 1.2sinx + 0.3 = 0
(sinx)^2 - 1.2sinx + 0.6^2 = -0.3 + 0.36
(sinx - 0.6)^2 = 0.06
sinx - 0.6 = ±sqrt(0.06)
sinx = 0.6 ± sqrt(0.06)
sinx = {0.54, 0.66}
if 0 <= x < 360
x = 32.6836388, 41.2998728, 138.700127, 147.316361
<span>4a^2-b^2+2a-b=</span>2а(2а-1) - b(b-1)