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

- PRE-CALC -
**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

- PRE-CALC -
**Steve**, Friday, December 9, 2011 at 11:52am
just draw the triangle

tan = y/x

sin = y/h

h = 5 (3-4-5 triangle!)

principal value of arctan(-4/3) is in QIV.

sin = -4/5

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