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November 26, 2015
Posted by **Jon** on Sunday, December 5, 2010 at 5:55pm.

- math -
**Reiny**, Sunday, December 5, 2010 at 6:16pmMake a triangle.

By Pythagoras

r^2 = 5^2 + 12^2

r = 13

so sinx = 5/13 and cosx = 12/13

I will assume you meant sin(x/2)

using cosx = 1 - 2sin^2 (x/2)

12/13 = 1-2sin^2 (x/2)

2sin^2 (x/2) = 1/13

sin^2 (x/2) = 1/26

sin (x/2) = 1/√26 or √26/26