Mathematics
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OpenStudy (maheshmeghwal9):
Please Solve:-
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OpenStudy (maheshmeghwal9):
\[\cos^{-1} (x)-\sin^{-1} (x)=0\]
OpenStudy (maheshmeghwal9):
Please solve for "x" :)
OpenStudy (maheshmeghwal9):
I have done as this:-
\[\cos^{-1} (x)-\sin^{-1} (x)+\sin^{-1} (x)=\sin^{-1} (x).\] \[\pi/2 = 2\sin^{-1} (x).\]
OpenStudy (asnaseer):
you can represent this in the following right angled triangle:
|dw:1338216489833:dw|
OpenStudy (asnaseer):
here:\[\cos(\theta)=\sin(\theta)=\frac{x}{1}=1\]so what is \(\theta\)?
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OpenStudy (asnaseer):
sorry - that should be an x at the right hand side
OpenStudy (asnaseer):
\[\cos(\theta)=\sin(\theta)=\frac{x}{1}=x\]
OpenStudy (maheshmeghwal9):
\[\sin^{-1} (x)\] or \[\cos^{-1} (x)\]
OpenStudy (asnaseer):
the equations I wrote can be rewritten as:\[\theta=\cos^{-1}(x)=\sin^{-1}(x)\]
OpenStudy (maheshmeghwal9):
so theta should be pi/4
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OpenStudy (asnaseer):
yes
OpenStudy (maheshmeghwal9):
& we get x=1/sqrt(2)
OpenStudy (asnaseer):
yes
OpenStudy (maheshmeghwal9):
but in my method I am getting 2 values for "x".\[(1/\sqrt{2}) ;-(1/\sqrt{2})\]
OpenStudy (maheshmeghwal9):
my method is stated above. please help:)
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OpenStudy (asnaseer):
how did you get to:\[\pi/2 = 2\sin^{-1} (x)\]
OpenStudy (maheshmeghwal9):
since in my course ; we state a property as:-\[\sin^{-1} (\alpha)+\cos^{-1} (\alpha)=\pi/2 \] Where alpha is an angle:)
OpenStudy (maheshmeghwal9):
did u get that:)
OpenStudy (asnaseer):
but by using this substitution you are losing the restriction that:\[\cos^{-1}(x)=\sin^{-1}(x)\]
OpenStudy (maheshmeghwal9):
k! thanx I got it:)
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OpenStudy (asnaseer):
so from your two solutions, you need to confirm which one satisfies the original problem
OpenStudy (asnaseer):
yw :)
OpenStudy (maheshmeghwal9):
:)