![image](https://tex.z-dn.net/?f=%5Clog_2%28%5Csin%5E22x%2B1%29-2%5Clog_2%5Ccos+x%3D1%2B%5Clog_25%3B%5C%5C+D%28f%29%3A%5C%5C+%5Cleft+%5C%7B+%7B%7B2%5Csin%5E22x%2B1%3E0%7D+%5Catop+%7B%5Ccos+x%3E0%7D%7D+%5Cright.+%5C+%5Cleft+%5C%7B+%7B%7B%5Csin%5E22x%2B1%3E0%2C%5C+%5Cforall+x%7D+%5Catop+%7B-%5Cfrac%7B%5Cpi%7D%7B2%7D%2B2%5Cpi+k%3Cx%3C%5Cfrac%7B%5Cpi%7D%7B2%7D%2B2%5Cpi+k%7D%7D+%5Cright.%5C%C2%A0+%2C+k%5Cin+Z%5C%5Cx%5Cin%5Cleft%28-%5Cfrac%7B%5Cpi%7D%7B2%7D%2B2%5Cpi+k%3B%5Cfrac%7B%5Cpi%7D%7B2%7D%2B2%5Cpi+k%5Cright%29%2C%5C+k%5Cin+Z)
0} \atop {\cos x>0}} \right. \ \left \{ {{\sin^22x+1>0,\ \forall x} \atop {-\frac{\pi}{2}+2\pi k0} \atop {\cos x>0}} \right. \ \left \{ {{\sin^22x+1>0,\ \forall x} \atop {-\frac{\pi}{2}+2\pi k
![image](https://tex.z-dn.net/?f=8%5Csin%5E2x%5Ccos%5E2x%2B1%3D10%5Ccos%5E2x%3B%5C%5C+%0A8%281-%5Ccos%5E2x%29%5Ccos%5E2x%2B1%3D10%5Ccos%5E2x%3B%5C%5C%0At%3D%5Ccos%5E2x%3D%3D%3E%5C+0%3Ct%5Cleq1%3D%3D%3E%5C+t%5Cin%280%3B1%5D%3B%5C%5C%0A8%281-t%29t%2B1%3D10t%3B%5C%5C%0A8t-8t%5E2%2B1%3D10t%3B%5C%5C%0A8t%5E2%2B2t-1%3D0%3B%5C%5C%0AD%3D2%5E2-4%5Ccdot8%5Ccdot%28-1%29%3D4%2B32%3D36%3D%28%5Cpm6%29%5E2%3B%5C%5C%0At_1%3D%5Cfrac%7B-2-6%7D%7B16%7D%3C0%5Cnotin%280%3B1%5D%3B%5C%5C%0At_1%3D%5Cfrac%7B-2%2B6%7D%7B16%7D%3D%5Cfrac%7B4%7D%7B16%7D%3D%5Cfrac14%5Ctin%280%3B1%5D%3B%5C%5C%0A%5Ccos%5E2x%3D%5Cfrac14%3B%5C%5C%0A%5Ccos+x%3E0%3B%5C%5C%0A%5Ccos+x%3D%5Cfrac12%3B%5C%5C%0Ax%3D%5Cpm%5Cfrac%5Cpi3%2B2%5Cpi+n%2C+n%5Cin+Z)
\ 0\ t\in(0;1];\\
8(1-t)t+1=10t;\\
8t-8t^2+1=10t;\\
8t^2+2t-1=0;\\
D=2^2-4\cdot8\cdot(-1)=4+32=36=(\pm6)^2;\\
t_1=\frac{-2-6}{16}<0\notin(0;1];\\
t_1=\frac{-2+6}{16}=\frac{4}{16}=\frac14\tin(0;1];\\
\cos^2x=\frac14;\\
\cos x>0;\\
\cos x=\frac12;\\
x=\pm\frac\pi3+2\pi n, n\in Z" alt="8\sin^2x\cos^2x+1=10\cos^2x;\\
8(1-\cos^2x)\cos^2x+1=10\cos^2x;\\
t=\cos^2x==>\ 0\ t\in(0;1];\\
8(1-t)t+1=10t;\\
8t-8t^2+1=10t;\\
8t^2+2t-1=0;\\
D=2^2-4\cdot8\cdot(-1)=4+32=36=(\pm6)^2;\\
t_1=\frac{-2-6}{16}<0\notin(0;1];\\
t_1=\frac{-2+6}{16}=\frac{4}{16}=\frac14\tin(0;1];\\
\cos^2x=\frac14;\\
\cos x>0;\\
\cos x=\frac12;\\
x=\pm\frac\pi3+2\pi n, n\in Z" align="absmiddle" class="latex-formula">