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Topic: equation with inverse trig fcn???HELP
Replies: 16   Last Post: Apr 14, 1998 8:10 PM

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kgray@InfoAve.Net

Posts: 54
Registered: 12/6/04
equation with inverse trig fcn???HELP
Posted: Apr 6, 1998 6:01 PM
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Given the equation : arcsin(3x-pi)=1/2

I solved it by taking the "sin" of both sides yielding the solution of
3x-pi = sin 1/2
so x= (pi +sin 1/2)(3)
or approximately 1.207006064...

One of my students solved this equation by saying:
Let u= 3x-pi

then arcsin(u) =1/2

then u= pi/6

so 3x-pi =pi/6
resulting in x = (pi +pi/6)/3 approximately equal to 1.22173...

Why are these solutions not equal??? I assume I am missing something.

Karol Gray
East Surry HS
Pilot Mountain, NC





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