Math Is Fun Forum

unique

Member

Registered: 2006-10-04

Posts: 419

Evaluate

ok i dont know how to do Arccos and Arcsin probelms...
such as these :

Evaluate :

Arcsin sqrt(2)
         ---------
            2

and then this one

Evaluate :

sin (Arccos 1  )
                ---
                 2

How to do these type of problems..

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Desi
Raat Key Rani !

mathsyperson

Moderator

Registered: 2005-06-22

Posts: 4,900

Re: Evaluate

You're probably meant to use some sin and cos values that you're meant to know.

Is it part of your syllabus to know the sin cos and tan values of 0, 30, 45, 60 and 90? If so, then just use them and the question should be fairly easy. If not, I think you'd just have to use a calculator. But I suspect it's the first.

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Why did the vector cross the road?
It wanted to be normal.

polylog

Member

Registered: 2006-09-28

Posts: 162

Re: Evaluate

It might probably be helpful to draw the reference triangles, and then thinking of arccos and arcsin as "the angle with the given sin or cos value", which you can read off of the reference triangle.

It's also helpful to notice that:

which is the value that is easiest to see in the 45 degree angle reference triangle.