Monday, October 14, 2013

If we know that sin(t) = 5/7 , how to find other identies like cos(t) and tan(t) ?

Given that sin(t) = 5/7, we need to find cos(x) and
tan(x)


We will use trigonometric identities to find
cos(x)


We know that sin^2 x + cos^2 x =
1


==> cosx = +-sqrt(1-sin^2
x)


Let us substitute with sinx =
5/7


==> cosx = +-sqrt(1-
(5/7)^2]


                = +-
sqrt(1-25/49)


                =
+-sqrt(24/49)


                = +-2sqrt6/
7


Then cosx = +- 2sqrt6 /
7


Now we know that tanx =
sinx/cosx


==> tanx = (5/7) / (+-2sqrt6 /
7)


                = +-
5/2sqrt6


               = +-5sqrt6/
12


==> tanx= +-5sqrt6 /
12

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