SOLUTION: find sin(u/2) if sec u=-11.351 and u is in quadrant II.

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Question 879358: find sin(u/2) if sec u=-11.351 and u is in quadrant II.
Answer by Edwin McCravy(20060) About Me  (Show Source):
You can put this solution on YOUR website!
On your TI-83 or 84,

type 11.351  (Caution, use the POSITIVE 11.351, not -11.351)!!!
press the x-1 key, read 11.351-1
press the ENTER key, read .0880970649
press the 2ND key
press the COS key, read cos-1(
press the 2ND key
press the (-) key, read cos-1(Ans
Press the ENTER key, read 84.94580618, which is in QI
To get it in QII
Type 180-
press the 2ND key
press the (-) key, read 180-Ans
press the ENTER key, Read 95.05419382
press the ÷ key, read Ans/
type 2, read Ans/2
press the ENTER key, read 47.52709691
press the SIN key, read sin(
press the 2ND key
press the (-) key, read sin(Ans
press the ENTER key, read .7375967614

Now go back and try to carefully ponder each step and figure out why we do it.
Any questions?.  Ask me in the thank-you note.


Edwin