Question #d0f7b

1 Answer
Nghi N
Dec 11, 2017

#sin (t/2) = (2sqrt5)/5#

Explanation:

Use trig identity:
#2sin^2 t = 1 - cos t#
In this case:
#2sin^2 t = 1 + 3/5 = 8/5#
#sin^2 t = 8/10 = 4/5#
#sin t = +- 2/sqrt5 = +- (2sqrt5)/5#
Since t is in Quadrant 2, sin t is positive.
#sin t = (2sqrt5)/5#

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