If #sin theta = -4/5# and #theta# is in the fourth quadrant, find #cos theta#?

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Answer 1 · 2018-02-02T04:06:49

#cos^2 t = 1 - sin^2 t = 1 - 16/25 = 9/25#
#cos t = +- 3/5#
Since t is in Quadrant 4, then, cos t is negative.
#cos t = - 3/5#