Find an algebraic expression equivalent to tan ( arc cos X )

Evaluate:

arc cos ( cos pi/3)

arc cos ( cos -pi/7)

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- Feb 24th 2008, 08:10 AMGodfatherAlgebraic Expressions in Trig.
Find an algebraic expression equivalent to tan ( arc cos X )

Evaluate:

arc cos ( cos pi/3)

arc cos ( cos -pi/7) - Feb 24th 2008, 08:57 AMTheEmptySet
- Feb 24th 2008, 09:16 AMTheEmptySet
For the second part....

We need to know the domain of the arc cosine function....

The domain is 0 to Pi.

also note that the cosine function is even ie

This gives us

so

and

since the angle is now in the domain of the arc sine function.