Oblicz wartość wyrażenia. Zapisz założenia. cos2α + tg²α - 1 + tg²αcos2α Powinno wyjść zero

[latex]cos2 alpha + tg^2 alpha - 1 + tg^2 alpha cos2 alpha=[/latex] [latex]cos2 alpha-1 + (tg^2 alpha+ tg^2 alpha cos2 alpha)=[/latex] [latex]1-2sin^2alpha-1 + tg^2 alpha(1+alpha cos2 alpha)=[/latex] [latex]-2sin^2alpha + frac{sin^2alpha}{cos^2alpha} (1+2cos^2 alpha-1)=[/latex] [latex]-2sin^2alpha + frac{sin^2alpha}{cos^2alpha} cdot 2cos^2 alpha=[/latex] [latex]-2sin^2alpha + 2sin^2alpha=0[/latex] [latex]cosalpha eq 0[/latex]