Prove sinx+cosx=x has a single solution

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SUMMARY

The equation sin(x) + cos(x) = x has a single solution in the interval [0, π/2]. To prove this, the Intermediate Value Theorem establishes the existence of at least one solution, while Rolle's Theorem confirms that there cannot be more than one solution in this interval. This conclusion is essential for understanding the behavior of trigonometric functions in relation to linear functions within specified bounds.

PREREQUISITES
  • Understanding of the Intermediate Value Theorem
  • Familiarity with Rolle's Theorem
  • Basic knowledge of trigonometric functions
  • Concepts of continuity and differentiability in calculus
NEXT STEPS
  • Study the Intermediate Value Theorem in detail
  • Explore Rolle's Theorem and its applications
  • Investigate the properties of sin(x) and cos(x) in the interval [0, π/2]
  • Learn about the implications of function continuity and differentiability
USEFUL FOR

Students of calculus, particularly those studying trigonometric equations and their solutions, as well as educators seeking to explain the concepts of the Intermediate Value Theorem and Rolle's Theorem.

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Homework Statement



Prove sinx+cosx=x has a single solution in [0, pi/2]



The Attempt at a Solution



This question seems very strange to me. How can I prove there is a single solution for every number between 0 and pi/2?

I'm not sure what formula to use.
I'm learning infinitesimal math.

Can someone help me out?
Thanks!
 
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mystmyst said:
This question seems very strange to me. How can I prove there is a single solution for every number between 0 and pi/2?
You are misreading the problem. You aren't supposed to show that that is "a single solution for every number between 0 and pi/2". In other words, you are supposed to show that there is
  1. A point x somewhere between 0 and pi/2 at which sinx+cosx=x.
  2. There are no other solutions in this interval.
 
mystmyst said:

Homework Statement



Prove sinx+cosx=x has a single solution in [0, pi/2]



The Attempt at a Solution



This question seems very strange to me. How can I prove there is a single solution for every number between 0 and pi/2?

I'm not sure what formula to use.
I'm learning infinitesimal math.

Can someone help me out?
Thanks!
I think you should use the intermediate value theorem to prove there is atleast one solution and rolles theorem to show that there can't be more than one solution.
 

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