Cos(x)+sin(x) = 0, Find all values?

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SUMMARY

The equation Cos(x) + Sin(x) = 0 has a primary solution at x = 3π/4. To find all solutions, one can add integer multiples of π to this value, resulting in an infinite series of solutions: x = 3π/4 + nπ, where n is any integer. The confusion regarding the value of Cos(7π/4) + Sin(7π/4) yielding a very small number (0.000000000021) is attributed to calculator precision errors, not a mistake in the mathematical approach.

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Homework Statement


Cos(x)+sin(x) = 0, Find all values?



Homework Equations





The Attempt at a Solution


I've found the first solution, which is 3pi/4 and I figured I can just add pi to that value over and over to obtain the infinite other values. But when I punch it in my calculator it's coming up that cos(7pi/4)+sin(7pi/4) = 0.000000000021

I'm not sure if this is a calculator computation issue or I'm doing something wrong.. Thanks for any help.
 
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DrummingAtom said:

Homework Statement


Cos(x)+sin(x) = 0, Find all values?



Homework Equations





The Attempt at a Solution


I've found the first solution, which is 3pi/4 and I figured I can just add pi to that value over and over to obtain the infinite other values. But when I punch it in my calculator it's coming up that cos(7pi/4)+sin(7pi/4) = 0.000000000021

I'm not sure if this is a calculator computation issue or I'm doing something wrong.. Thanks for any help.
No, you're not doing anything wrong. This error is due to the calculator.
 

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