Question 378343
If x is a positive angle smaller than 90° and cos(x) = 1/3, then sin(x) = 
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{{{sin^2(x) + cos^2(x) = 1}}}
{{{sin(x) = sqrt(1 - cos^2(x)) = sqrt(1 - 1/9) = sqrt(8/9)}}}
{{{sin(x) = 2sqrt(2)/3}}}
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PS  Giving the choices is a waste of time.