The value of sin 120.?

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Answer 1 · 2018-03-14T05:06:34

$\frac{\sqrt{3}}{2}$

Use the following trigonometric identity to rewrite the given angle $\ \ \ \sin (x)=\cos (90^{\circ }-x)\ \ \$ as:

$\sin (120^{\circ })=\cos (90^{\circ }-120^{\circ })$

$=\cos (-30^{\circ })$

Keep remember that, $\ \ cos\ \$ is an even function such that $\ \ \cos (-x)=\cos (x)\ \$

$\cos (-30^{\circ })=\cos (30^{\circ })$

$=\frac{\sqrt{3}}{2}$

That's it!