Trig Help !

[Sumboody]

cos(x)=0.6 and is in the 4th quadrant, how do i find sin(x/2) ?

[DannyN]

you can inverse cos(x)=0.6 to get an angle, your calculator would probably give you an angle in the first quadrant
i got x=53.13 degrees ,so it would be -53.13 degrees in the forth quadrant

then sub x=-53.13 into sin(x/2)=sin(-53.13/2) which gives you -.447

[Sumboody]

Thanks
but is it possible without a calculator?

[kamil9876]

Use:



If you want.

[pi]

Draw a triangle and use pythag, and then create the half angle formula with

Use:



If you want.