How can I add labels to a plot?

Question

I have created five lines in a plot.

Plot[Table[1 + (k - 1)*Sin[theta]^2, {k, 0, 2, 0.5}], {theta, 0, 
Pi/2}, PlotRange -> {{0, Pi/2}, {0, 2}}]

And I want to add five labels for them each other.I used PlotLabels \ such as this :

PlotLabels -> {"a=0", "a=0.5", "a=1.0", "a=1.5", "a=2.0"}

But I get a picture with only one label. I want to get fives of each other.

Answer 1

Plot[Evaluate@Table[1 + (k - 1)*Sin[theta]^2, {k, 0, 2, 0.5}], {theta, 0, Pi/2}, 
PlotRange -> {{0, Pi/2}, {0, 2}}, PlotLabels -> {"a=0", "a=0.5", "a=1.0", "a=1.5", "a=2.0"}]

In response to your comment,

Plot[Evaluate@Table[1 + (k - 1)*Sin[theta]^2, {k, 0, 2, 0.5}], {theta,
   0, Pi/2}, PlotRange -> {{0, Pi/2}, {0, 2}}, 
 PlotLabels -> {Subscript["I", 3]/Subscript["I", 1] == 0, "a=0.5", 
   "a=1.0", "a=1.5", "a=2.0"}]