SOLUTION: Hi can someone help me with this problem please? THANK YOU! Simplify the expression cos^-1[sin(-pi/6)]

Algebra ->  Trigonometry-basics -> SOLUTION: Hi can someone help me with this problem please? THANK YOU! Simplify the expression cos^-1[sin(-pi/6)]      Log On


   

Question 1076558: Hi can someone help me with this problem please? THANK YOU!
Simplify the expression cos^-1[sin(-pi/6)]
Found 2 solutions by stanbon, Edwin McCravy:
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
Simplify the expression cos^-1[sin(-pi/6)]
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Note:: sin(-pi/6) = -1/2
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And cos^-1(-1/2) = (5/6)pi or (7/6)pi
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Cheers,
Stan H.
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Answer by Edwin McCravy(20054) About Me  (Show Source):
You can put this solution on YOUR website!


The other tutor is right that matrix%281%2C3%2Csin%28-pi%2F6%29%2C%22%22=%22%22%2C-1%2F2%29

But the rest is wrong because



Since he gave two answers, even though they are wrong, the
fact that he gave two answers instead of one shows that he
has forgotten that inverse trig functions are indeed 
functions.  Functions cannot have two output values for the 
same input value.  The range of the inverse cosine function 
is [0,p) 

So 2pi%2F3 is the only value.

Edwin