How Do You Solve a Quadratic Trigonometric Equation?

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SUMMARY

The discussion focuses on solving the quadratic trigonometric equation 6sin²(x) - 6sin(x) + 1 = 0 for the interval 0 ≤ x ≤ 2π. Participants suggest substituting sin(x) with a variable y, transforming the equation into 6y² - 6y + 1 = 0, which can be solved using the quadratic formula. The solutions for y correspond to the values of sin(x), leading to two goniometric equations that can be solved for x. The conversation emphasizes that treating the equation as a quadratic function is valid and effective.

PREREQUISITES
  • Understanding of trigonometric functions, specifically sine.
  • Familiarity with quadratic equations and the quadratic formula.
  • Knowledge of inverse trigonometric functions.
  • Basic algebraic manipulation skills.
NEXT STEPS
  • Practice solving quadratic equations using the quadratic formula.
  • Explore the properties of inverse trigonometric functions.
  • Learn about the binomial theorem and its applications in algebra.
  • Study the relationship between trigonometric functions and their algebraic counterparts.
USEFUL FOR

Students studying trigonometry, particularly those tackling quadratic trigonometric equations, as well as educators looking for effective methods to teach these concepts.

ku07
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How do you algebraicly find the solution to this equation

6sin(to power of 2)x-6sinx+1=0

where 0<(or equal to) x <(or equal to) 2pi
 
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Let Sinx = u and then use the binomial theorem.
 
ku07 said:
How do you algebraicly find the solution to this equation

6sin(to power of 2)x-6sinx+1=0

where 0<(or equal to) x <(or equal to) 2pi
If you replace sin(x) by a variable y your equation will be :

6y^2 -6y + 1 = 0

Solve this equation for y. You will get maximum two solutions for y. each solution is equal to sin(x), so you will get two goniometric equations that will be easy to solve.

marlon
 
Im in trig as well and I am confused with some of yalls answers. Couldn't he treat this as a quadratic function. If it were me I would see if I could factor it then set each to 0 and solve; if it doesn't factor I would plug it in the quadratic formula and solve. I am in this same chapter of trig so please let me konw what I am overlooking.
 
seanistic said:
Im in trig as well and I am confused with some of yalls answers. Couldn't he treat this as a quadratic function. If it were me I would see if I could factor it then set each to 0 and solve; if it doesn't factor I would plug it in the quadratic formula and solve. I am in this same chapter of trig so please let me konw what I am overlooking.

yes you can treat it as a quadratic function, that's what marlon did in his post, although you could just leave sin (x) instead of replacing it with y, I believe that just plugging sin(x) = quadratic formula would work just as well, you would then have to do inverse sin on both sides to solve for x
 

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