Trig General Solution: Solve for x using sin2x = 0.5

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SUMMARY

The general solution for the equation sin2x = 0.5 is derived using the arcsine function and the properties of sine. The solutions are x = 15 degrees + k180 and x = 75 degrees + k180, where k is any integer. It is crucial to recognize that using arcsine can lead to missing solutions in the second quadrant, which is addressed by considering both 30 degrees and 150 degrees as potential angles for 2x. The complete solution includes both forms: 2x = arcsin(0.5) + 2kπ and 2x = π - arcsin(0.5) + 2kπ.

PREREQUISITES
  • Understanding of trigonometric identities, specifically sin2x = 2sinxcosx.
  • Familiarity with the arcsine function and its implications in trigonometry.
  • Knowledge of general solutions in trigonometric equations.
  • Basic understanding of radians and degrees in angle measurement.
NEXT STEPS
  • Study the unit circle to better understand the sine function and its periodicity.
  • Learn about the properties of inverse trigonometric functions, particularly arcsin.
  • Explore the concept of general solutions for trigonometric equations in different quadrants.
  • Practice solving similar trigonometric equations using various methods, including graphical approaches.
USEFUL FOR

Students studying trigonometry, educators teaching trigonometric equations, and anyone looking to deepen their understanding of solving periodic functions.

GrandMaster87
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Homework Statement


Solve for x using general solution
sin2x = 0.5



Homework Equations


sin2x= 2sinxcosx


The Attempt at a Solution


arcsin0.5 = 2x
2x = 30 degrees + k360
x = 15 degrees + k180.

Or

2x = (180-30) + k360
2x = 150 + k360
x = 75 + k180
 
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GrandMaster87 said:

Homework Statement


Solve for x using general solution
sin2x = 0.5



Homework Equations


sin2x= 2sinxcosx


The Attempt at a Solution


arcsin0.5 = 2x
2x = 30 degrees + k360
x = 15 degrees + k180.

Or

2x = (180-30) + k360
2x = 150 + k360
x = 75 + k180

Using the arcsine is dangerous since you miss solutions in the second quadrant.

sin2x = 1/2 ==> 2x = 30º + k360º or 150º + k360º

Continue from there.

--Elucidus
 
2x=arcsin(0.5)+2kп

2x=п-arcsin(0.5) +2kп
 

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