trig
posted by Steve .
Find sin è/2 for sin è = 1/4 and è lies in Quadrant I.

I am going to use
cos 2A = 1  2sin^2 A
or
cos è = 1  2sin^2 (è/2)
so we first have to know cos è
make a diagram using sin è = 1/4
then cos è = √15/4
back in our equation...
√15/4 = 1  2sin^2 (è/2)
which solves to √[(4√15)/8]
(I tested my answer on a calculator)
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