Wednesday, May 1, 2013

Solve for the exact solutions arcsin(x)+arctan(x)=0

Solution:



arcsin%28x%29%2Barctan%28x%29=0 

arctan%28x%29=-arcsin%28x%29 

arcsine is an odd function so we "pull" the negative sign into the input... 

arctan%28x%29=arcsin%28-x%29 

tan%28arctan%28x%29%29=tan%28arcsin%28-x%29%29 

The tangent of arcsine is... 
x%2Fsqrt%281-x%5E2%29 


so we simplify... 
x=%28-x%29%2Fsqrt%281-x%5E2%29 
x%2Asqrt%281-x%5E2%29=-x 
x%2Asqrt%281-x%5E2%29%2Bx=0 
x%2A%28sqrt%281-x%5E2%29%2B1%29=0 
By the zero product rule 
x=0 
or 
sqrt%281-x%5E2%29%2B1=0 
But the equation can never have a real solution (why?) 

...so x=0

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