из первого уравнения выразим переменную у.
![\displaystyle \left \{ {{5x-y=11} \atop {-10x+2y=-22}} \right.~~\Longleftrightarrow~~\left \{ {{y=5x-11} \atop {-10x+2(5x-11)=-22}} \right.\\ \\ \\ -10x+10x-22=-22\\ \\ -22=-22](https://tex.z-dn.net/?f=%5Cdisplaystyle+%5Cleft+%5C%7B+%7B%7B5x-y%3D11%7D+%5Catop+%7B-10x%2B2y%3D-22%7D%7D+%5Cright.~~%5CLongleftrightarrow~~%5Cleft+%5C%7B+%7B%7By%3D5x-11%7D+%5Catop+%7B-10x%2B2%285x-11%29%3D-22%7D%7D+%5Cright.%5C%5C+%5C%5C+%5C%5C+-10x%2B10x-22%3D-22%5C%5C+%5C%5C+-22%3D-22)
Это уравнение верно для любых х, т.е. уравнение имеет бесконечно много решений
Все, можешь ловить решение!
1. 1=sin²a+cos²a
cosa=
![\frac{3}{5}](https://tex.z-dn.net/?f=+%5Cfrac%7B3%7D%7B5%7D+)
sina=
![\sqrt{1- (\frac{3}{5}) ^{2} } = \sqrt{ \frac{25}{25}- \frac{9}{25} } = \sqrt{ \frac{16}{25}} = \frac{4}{5} ](https://tex.z-dn.net/?f=+%5Csqrt%7B1-+%28%5Cfrac%7B3%7D%7B5%7D%29+%5E%7B2%7D+%7D+%3D+%5Csqrt%7B+%5Cfrac%7B25%7D%7B25%7D-+%5Cfrac%7B9%7D%7B25%7D++%7D+%3D++%5Csqrt%7B+%5Cfrac%7B16%7D%7B25%7D%7D+%3D+%5Cfrac%7B4%7D%7B5%7D+%0A)
tga=
![\frac{sina}{cosa}](https://tex.z-dn.net/?f=+%5Cfrac%7Bsina%7D%7Bcosa%7D+)
ctga=
![\frac{cosa}{sina}](https://tex.z-dn.net/?f=+%5Cfrac%7Bcosa%7D%7Bsina%7D+)
Расписывать долго. посчитаешь. если не можешь то пиши
2. cos
⁴a+sin²acos²a=cos²a(cos²a+sin²a)=cos²a*1=cos²a
![\frac{2sin ^{2} a-1}{sina+cosa} = \frac{2sin ^{2} a- sin^{2}a-cos ^{2} a }{sina+cosa} = \frac{ sin^{2}a- cos^{2}a }{sina+cosa} = \frac{(sina+cosa)(sina-cosa)}{sina+cosa}](https://tex.z-dn.net/?f=+%5Cfrac%7B2sin+%5E%7B2%7D+a-1%7D%7Bsina%2Bcosa%7D+%3D+%5Cfrac%7B2sin+%5E%7B2%7D+a-+sin%5E%7B2%7Da-cos+%5E%7B2%7D+a+%7D%7Bsina%2Bcosa%7D+%3D+%5Cfrac%7B+sin%5E%7B2%7Da-+cos%5E%7B2%7Da++%7D%7Bsina%2Bcosa%7D+%3D+%5Cfrac%7B%28sina%2Bcosa%29%28sina-cosa%29%7D%7Bsina%2Bcosa%7D)
=sina-cosa
<span> b4= - 1,b7 = 27</span>
bn=b1*q^n-1
b1*q3=-1
b1*q6=27
b1=-1/q^3
(-1/q^3)*q^6=27
-q^3=27
q^3=-27
q=-3