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79. :

, 31 2008 . 23:58 +
SerenityJames , - ]:->

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Problem: Find sin(x), if cos(x) = 4/5 and 0 < x < /2.


Solution: It is known that sin(x)^2 + cos(x)^2 = 1 or (4/5)^2 + sin(x)^2 = 1.

sin(x)^2 = 1 - 16/25 = 9/25, |sin(x)| = sin(x) = sqrt(9/25) = 3/5.

Answer: 3/5.

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: sin(x), cos(x) = 4/5 0 < x < /2.



: , sin(x)^2 + cos(x)^2 = 1 or (4/5)^2 + sin(x)^2 = 1.

sin(x)^2 = 1 - 16/25 = 9/25, |sin(x)| = sin(x) = sqrt(9/25) = 3/5.

: 3/5.
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