[latex]pi rad=180^0[/latex] [latex]1 rad=(frac{180}{pi})^0[/latex] [latex]1^0=frac{pi}{180} rad[/latex] 1. [latex]135^0=135cdotfrac{pi}{180} rad=frac{3}{4} rad[/latex] [latex]75^0=75cdotfrac{pi}{180} rad=frac{5}{12}pi rad[/latex] [latex]15^0=15cdotfrac{pi}{180} rad=frac{pi}{12} rad[/latex] 2) [latex]-frac{1}{6}pi=2pi-frac{1}{6}pi=frac{11}{6}pi=frac{11}{6}picdotfrac{180^0}{pi}=\=330^0[/latex] lub; [latex]-frac{1}{6}pi=-frac{1}{6}cdot180^0=-30^0[/latex] [latex]3pi=3picdotfrac{180^0}{pi}=540^0[/latex] [latex]frac{3}{4}pi=frac{3}{4}cdot180^0=135^0[/latex] 3. [latex]sin^4x-cos^4x=frac{1}{2}\(sin^2x+cos^2x)(sin^2x-cos^2x)=frac{1}{2}\1cdot(sin^2x-cos^2x)=frac{1}{2}\cos^2x=1-sin^2x\sin^2x-1+sin^2x=frac{1}{2}\2sin^2x=frac{3}{2}\sin^2x=frac{3}{4}\sinx=frac{sqrt{3}}{2} vee sinx=-frac{sqrt{3}}{2}\x=frac{1}{6}pi+2kpi vee x=frac{5}{6}pi+2kpi vee x=frac{7}{6}pi+2kpi vee x=frac{11}{6}pi+2kpi[/latex] [latex]x=frac{1}{6}pi+kpi vee x=frac{5}{6}pi+kpi[/latex]
