SOLUTION: 1-sinx/cosx=cosx/1+sinx

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Question 969538: 1-sinx/cosx=cosx/1+sinx
Answer by KMST(5328) About Me  (Show Source):
You can put this solution on YOUR website!
NOTE:
I believe you meant %281-sin%28x%29%29%2Fcos%28x%29=%281-sin%28x%29%29%2Fcos%28x%29%29 .
If that was not what you meant, then I solved the wrong problem.

You could write %281-sin%28x%29%29%2Fcos%28x%29=%281-sin%28x%29%29%2Fcos%28x%29%29 as
(1-sinx)/cosx=cosx/(1+sinx) , because
1-sin(x)/cos(x)=1-sin%28x%29%2Fcos%28x%29 and cos(x)/1+sin(x)=cos%28x%29%2F1%2Bsin%28x%29 .
The parentheses are implicit in %281-sin%28x%29%29%2Fcos%28x%29=%281-sin%28x%29%29%2Fcos%28x%29%29 .
The long horizontal line between numerator and denominator is a powerful grouping symbol that indicates that numerator and denominator must be calculated before doing the division.
When you cannot write two lines (as when you are entering calculations into a calculator or spreadsheet) you need to write the implicit parentheses.

The expressions in %281-sin%28x%29%29%2Fcos%28x%29=cos%28x%29%2F%281%2Bsin%28x%29%29 do not exist (are undefined) when the denominators are zero.
cos%28x%29=0 happens for x=pi%2F2 , x=3pi%2F2 , and all co-terminal angles.
In general, we could say that x=%282k%2B1%29pi%2F2 for every integer k
makes cos%28x%29=0 and cannot be a solution to the equation above.

The values of x that make 1%2Bsin%28x%29=0<--->sin%28x%29=-1 are
3pi%2F2 and all co-terminal angles.
Those values will be excluded if we exclude x=%282k%2B1%29pi%2F2 for every integer k
to make cos%28x%29%3C%3E0 .
As long as x%3C%3E%282k%2B1%29pi%2F2 for every integer k ,
which makes cos%28x%29%3C%3E0 and cos%28x%29%3C%3E0 , we can multiply both sides of
%281-sin%28x%29%29%2Fcos%28x%29=cos%28x%29%2F%281%2Bsin%28x%29%29 times cos%28x%29%281%2Bsin%28x%29%29
to get the equivalent equations
--->%281-sin%28x%29%29%281%2Bsin%28x%29%29=cos%28x%29cos%28x%29--->1-sin%5E2%28x%29=cos%5E2%28x%29 ,
and since the last equation is a trigonometric identity,
true for all values of x ,
the solution to 1-sin%5E2%28x%29=cos%5E2%28x%29 is all values of x ,
and the solution to %281-sin%28x%29%29%2Fcos%28x%29=cos%28x%29%2F%281%2Bsin%28x%29%29
is all values of x such that x%3C%3E%282k%2B1%29pi%2F2 for every integer k .