Understanding the Two Solutions for Integrating (sin(t)cos(t))

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Discussion Overview

The discussion revolves around the integral of (sin(t)cos(t)), specifically addressing the two proposed solutions: {(sint)^2}/2 and {-(cost)^2}/2. Participants explore the implications of these solutions in the context of indefinite integrals and their application in differential equations.

Discussion Character

  • Exploratory
  • Mathematical reasoning

Main Points Raised

  • One participant states that the integral of (sin(t)cos(t)) has two possible solutions, which are not the same but yield the same values for definite integrals.
  • Another participant notes that indefinite integrals can vary by an additive constant, suggesting that the two functions differ by a constant.
  • A further elaboration indicates that since sin^2(t) + cos^2(t) = 1, the two solutions can be expressed in terms of each other, differing by the constant "-1/2".

Areas of Agreement / Disagreement

Participants acknowledge that both proposed solutions are valid in the context of indefinite integrals, but there is no consensus on how to choose between them for specific problems, particularly in differential equations.

Contextual Notes

The discussion highlights the dependence on additive constants in indefinite integrals and the implications for different applications, such as differential equations, without resolving the choice of solution for specific cases.

Who May Find This Useful

Readers interested in integral calculus, particularly those exploring the nuances of indefinite integrals and their applications in differential equations.

Danish_Khatri
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The integral of (sin(t)cos(t)) has two possible solutions: {(sint)^2}/2 and {-(cost)^2}/2 eventhough these two function are not same. Although these both solutions give same values for the definite integrals, different results are obtained when such integration appears when solving differential equations. I need some help to get out of this confusion and need to know how do we choose which solution we should use for a given problem
 
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Indefinite integrals can vary by an additive constant (the +C at the end). The two functions you have only vary by a constant.
 
Danish_Khatri said:
The integral of (sin(t)cos(t)) has two possible solutions: {(sint)^2}/2 and {-(cost)^2}/2 eventhough these two function are not same. Although these both solutions give same values for the definite integrals, different results are obtained when such integration appears when solving differential equations. I need some help to get out of this confusion and need to know how do we choose which solution we should use for a given problem
Any (indefinite) integral has an infinite number of different solutions- but they all differ by added constants. In this particular case, since sin^2(t)+ cos^2(t)= 1, cos^2(t)= 1- sin^2(t) so -cos^2(t)/2= -(1- sin^2(t))/2= -1/2+ sin^2(t)/2. Your two solutions differ by the constant "-1/2".
 
Thanks a lot... The replies were really helpful
 

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