The two acute angles of a right triangle have degree measures of x and y. If #sin#x = #5/13#, what is the value of #cos# y?

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Answer 1 · 2018-05-18T16:42:33

#cos y = 5/13#

#x# and #y# are complementary.

#sin x = 5/13 = (opp)/(hyp)#

However, the side opposite (opp) the angle #x# is also the side adjacent (adj) to angle #y#.

#cos y = (adj)/(hyp) = 5/13#

Answer 2 · 2018-05-18T17:51:21

# 5/13#.

Clearly, #x+y=90^@#.

#:. y=90^@-x#.

#:. cosy=cos(90^@-x)=sinx=5/13#, as Respected Mr. Hsia

has readily derived!