Wikipedia:Reference desk/Archives/Mathematics/2012 June 7

= June 7 =

LaTeX multiplication symbol
I want to insert the multiplication symbol ("×") between the 20 and 80 and again between the 30 and 90 in the following equation:

$$ \bar{x} = \frac{(20)(80) + (30)(90)}{20 + 30} = 86. $$

But, LaTeX chokes on it:

$$ \bar{x} = \frac{(20)×(80) + (30)×(90)}{20 + 30} = 86. $$

What do I need to change ? StuRat (talk) 03:50, 7 June 2012 (UTC)


 * LaTeX does not know what "×" is (it's not ASCII, and support for other encodings is somewhat complicated). Use \times:
 * $$\bar{x} = \frac{(20)\times(80) + (30)\times(90)}{20 + 30} = 86.$$
 * --Stephan Schulz (talk) 03:57, 7 June 2012 (UTC)


 * Excellent. Thanks, I'll mark this Q resolved. StuRat (talk) 04:00, 7 June 2012 (UTC)


 * Honk if you struggle with an urge to edit this section only to correct that which causes the error. —Tamfang (talk) 23:24, 11 June 2012 (UTC)

Diameter of circle that circumscribes equilateral triangle; should be easy?
I'm trying to calculate the diameter of a circle which circumscribes an equilateral triangle of side 1 cm. It's been nine years since I did my A levels (I got an A, btw). According to 2R = a/sinA, 1 cm / sin60 = 0.87 cm but that makes no sense. If I get a cylinder of internal diameter 0.86 cm, no way can I squeeze such a triangle into it! --2.120.147.92 (talk) 15:27, 7 June 2012 (UTC)


 * sin(60) = 0.867, so 1 / sin(60) = 1.155 cm (to 3 d.p.). Gandalf61 (talk) 16:34, 7 June 2012 (UTC)