Question

What is `sin(120^circ)`?

Answer 1

`sin(120^circ)=sqrt(3)/2`

Explanation:

From the diagram above, we see that `120^circ` is equivalent to a reference angle of `60^circ` in Quadrant II.

Using standard triangles (as in the image) we see that the ratio of the height (derived using the Pythagorean Theorem) to the hypotenuse is `sqrt(3)/2`.
This ratio is (by definition) the value of `sin`

It should be acknowledged that if you want this value in a non-radical (approximation) form, then you will need to use a calculator to find `sqrt(3)`, in which case you might as well use the calculator to look up `sin(120^circ)` directly.