Can't understand Inkscape tutorial

[jarlath]

I'm doing an inkscape tutorial where you make a flag of the EU.
http://tavmjong.free.fr/INKSCAPE/MAN...ExampleEU.html

At the end, the author explains the positioning of the stars in terms of mathematics;

Next, select the original star and make a new Clone. This time move the Clone 60 pixels downward direction (-60). Repeat for the Horizontal (x) direction. For the rest of the stars use the eight permutations of x(y) = ±30 and y(x) = ±52 pixels (60 times the sine and cosine of 30° respectively).

It's the bold part I don't understand. I've tried getting the COS and SINE of these numbers but the resulting figures (even when multiplied by said '60') don't position the stars correctly.

If anyone can help here I'd appreciate it. I did contact the author a few days ago, but I'd like to get on with the tutorial and it's probably something I should know.

Thanks,
Jarlath