Question

(1-cos4x/cos^-2(2a) -1) + (1+cos4a/sin^-2(2a) -1)

Answer 1

$\frac{1-Cos4\alpha }{Cos^{-2}2\alpha-1} +\frac{1+Cos4\alpha}{Sin^{-2}2\alpha-1}=\frac{2Sin^{2}2\alpha}{\frac{1}{Cos^{2}2\alpha}-1 }+\frac{2Cos^{2}2\alpha}{\frac{1}{Sin^{2}2\alpha} -1}=\frac{2Sin^{2}2\alpha}{\frac{1-Cos^{2}2\alpha}{Cos^{2}2\alpha}}+\frac{2Cos^{2}2\alpha}{\frac{1-Sin^{2}2\alpha}{Sin^{2}2\alpha}}=\\\\=\frac{2Sin^{2}2\alpha Cos^{2} 2\alpha}{1-Cos^{2}2\alpha}+\frac{2Sin^{2}2\alpha Cos^{2} 2\alpha}{1-Sin^{2}2\alpha}=\\$

$=\frac{2Sin^{2}2\alpha Cos^{2} 2\alpha}{Sin^{2}2\alpha}+\frac{2Sin^{2}2\alpha Cos^{2} 2\alpha}{Cos^{2}2\alpha}=2Cos^{2} 2\alpha+2Sin^{2}2\alpha= \\\\=2(Cos^{2} 2\alpha+Sin^{2}2\alpha)=2*1=\boxed2$