Question 857597
In quadrant 4, the sin is negative
and the cos is positive
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{{{ cos( theta ) = sqrt( 13^2 - 5^2 ) / 13 }}}
{{{ cos( theta ) = sqrt( 169 - 25 ) / 13 }}}
{{{ cos( theta ) = sqrt( 144 ) / 13 }}}
{{{ cos( theta ) = 12/13 }}}