Proszę o pomoc!! zadanie 6.10 tylko przykład b, d a z 6.12 przykład c. zadania w załącznikach. Z góry dzięki ;)

6.10a a: [latex]sin ^{2} alpha - 2 + cos^{2} alpha = 1 - 2 = -1[/latex] b: [latex]tg alpha cos alpha - sin alpha = frac{sin alpha }{cos alpha } cos alpha - sin alpha = sin alpha -sin alpha =0[/latex] c: [latex](1+tg^{2} alpha )cos^{2} alpha - 5 = cos^{2} alpha + sin^{2} alpha - 5 = 1 -5 = -4[/latex] d: [latex](1 - cos alpha)(1 + cos alpha) - sin^{2} alpha = 1 - cos^{2} alpha - sin^{2} alpha = 1 - 1 = 0[/latex] 6.12 a: [latex](sin alpha +cos alpha )^2 = sin^{2} alpha + 2 sin alpha cos alpha + cos^{2} alpha = 1 + 2 sin alpha cos alpha[/latex] b: [latex]sin^{4} alpha - cos^{4} alpha = (sin^{2} alpha - cos^{2} alpha )(sin^{2} alpha + cos^{2} alpha )=sin^{2} alpha - cos^{2} alpha[/latex] c: [latex] frac{1}{cos^2 alpha} } -1= frac{1}{cos^2 alpha} }- frac{cos^{2} alpha }{cos^2 alpha} }= frac{1-cos^2 alpha }{cos^2 alpha}} = frac{sin^2 alpha}{cos^2 alpha}} =tg^2 alpha [/latex]