# Missing part in answer to 10.7, exercise 91 Classic List Threaded 2 messages The exercise description says: In Exercises 87 - 92, solve the inequality.  Express the exact answer in interval notation, restricting your attention to−2PI≤x≤2PI 91. sin(2x) >= sin(x) The answer is missing one interval (actually one point) [2PI,2PI] According to the description 2PI is part of the domain to consider and in this point sin(2x) is equal to sin(x). So as far as I understand the full answer should be: [-2PI,-5PI/3]U[-PI,-PI/3]U[0,PI/3]U[PI,5PI/3]U[2PI,2PI] Of course I could be wrong, or I missed something in this exercise.
 Administrator Thank you! On Tuesday, May 7, 2019, 4:27:27 PM EDT, Adam [via Stitz Zeager Open Source Mathematics] <[hidden email]> wrote: The exercise description says: In Exercises 87 - 92, solve the inequality.  Express the exact answer in interval notation, restricting your attention to−2PI≤x≤2PI 91. sin(2x) >= sin(x) The answer is missing one interval (actually one point) [2PI,2PI] According to the description 2PI is part of the domain to consider and in this point sin(2x) is equal to sin(x). So as far as I understand the full answer should be: [-2PI,-5PI/3]U[-PI,-PI/3]U[0,PI/3]U[PI,5PI/3]U[2PI,2PI] Of course I could be wrong, or I missed something in this exercise. If you reply to this email, your message will be added to the discussion below: http://stitz-zeager-open-source-mathematics.2325449.n4.nabble.com/Missing-part-in-answer-to-10-7-exercise-91-tp459.html To start a new topic under Stitz Zeager Open Source Mathematics, email [hidden email] To unsubscribe from Stitz Zeager Open Source Mathematics, click here. NAML