Posted by Billy NEED HELP on Friday, December 9, 2011 at 11:41am.
sin(arctan(4/3)
okay so i made arctan(4/3) = x
so im solving for sin(x)
and x= arctan(4/3)
so then tanx = 4/3
and now im stuck i don't know what to do after that

PRECALC  Damon, Friday, December 9, 2011 at 11:52am
Draw the right triangle (3,4,5)
3^2+4^2 = 9+16 = 25 = 5^2
angle A = atan(4/3)
sin A = 4/5
now look for quadrant
tan = 4/3 in quadrant 2 and in quadrant 4
in quadrant 2 sin A = 4/5
in quadrant 4 sin A = 4/5 
PRECALC  Steve, Friday, December 9, 2011 at 11:52am
just draw the triangle
tan = y/x
sin = y/h
h = 5 (345 triangle!)
principal value of arctan(4/3) is in QIV.
sin = 4/5