1-2sin^2(a)+sin^4(a)/1-2cos^2(a)+co s^4(a)

[tex]\displaystyle\tt\boxed{\cos^2\alpha+\sin^2\alpha=1} \frac{1-2\sin^2\alpha+\sin^4\alpha}{1-2\cos^2\alpha+\cos^4\alpha}=\frac{(1-\sin^2\alpha)^2}{(1-\cos^2\alpha)^2}=(\frac{\cos^2\alpha}{\sin^2\alpha})^2=(ctg^2\alpha)^2=ctg^4\alpha[/tex]

шир x -4 длина x    s=x*(x-4)    (x-2)*(x-3)=x*(x-4)-6  x^2-4x+6=x^2-5x-6

x=12  (дм) длина 12-4=8 ширина