Plot[{Cos[t], Sin[t]}, {t, -Pi, Pi}]

Plot[{Sqrt[1 - x^2], -Sqrt[1 - x^2]}, {x, -1, 1}]

ParametricPlot[{Cos[t], Sin[t]}, {t, 0, 2  Pi}]

Plot[Exp[x], {x, -1, 1}]

ParametricPlot[{x, Exp[x]}, {x, -1, 1}]

D[Sin[x], x]

Derivative[1][Sin]

Sin'

D[Sin[x], {x, 2}]

Derivative[2][Sin]

Sin''

Limit[Sin[w]/w, w -> 0]

Sum[i^3, {i, 15}]

Sum[n!, {n, 3, 10}]

Sum[(1/2)^v, {v, 0, 100}]

Product[1 - 1/w, {w, 5, 25}]

Sum[x^k/k!, {k, 0, Infinity}]

Plot[Sin[x], {x, -Pi, Pi}, AspectRatio -> Automatic, 
      AxesLabel -> {x, y}, PlotRange -> {-5/2, 5/2}]