Satisfying trig equations between (0,2pi)

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In summary, the conversation discusses a problem involving a quadratic equation with cos x as the variable. The person has attempted to solve it using trig identities and as a trinomial, but has had no success. They ask for help in solving the equation.
  • #1
banfill_89
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Homework Statement


cos^2 x-cos x- 1= 0


Homework Equations


several trig identities involving cos


The Attempt at a Solution


i tried applying identites everywhere, no luck. I've tried using it as a trinomial...no luck...and I've tried adding one to both sides and still no luck...please help lol
 
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  • #2
banfill_89 said:

Homework Statement


cos^2 x-cos x- 1= 0


Homework Equations


several trig identities involving cos


The Attempt at a Solution


i tried applying identites everywhere, no luck. I've tried using it as a trinomial...no luck...and I've tried adding one to both sides and still no luck...please help lol

If you squint your eyes a bit, you might notice that this is a quadratic in cos x. Think about how you would solve x^2 - x - 1 = 0, but keep in mind that you're solving for the cosine of x, not x.
 

1. What is the purpose of satisfying trig equations between 0 and 2pi?

The interval between 0 and 2pi is known as one "cycle" of the unit circle, meaning that values within this range will repeat themselves. Therefore, solving trig equations within this interval allows us to find all possible solutions for a given equation.

2. How do you solve trig equations between 0 and 2pi?

To solve trig equations in this interval, we use the properties of trigonometric functions such as sine, cosine, and tangent, along with algebraic techniques. We manipulate the equation to isolate the variable and then use inverse trigonometric functions to find the solutions within the given interval.

3. Can a trig equation have multiple solutions between 0 and 2pi?

Yes, a trig equation can have multiple solutions within this interval. This is because the trigonometric functions are periodic, meaning that they repeat themselves every 2pi. Therefore, there can be an infinite number of solutions within this range.

4. Are there any special cases when solving trig equations between 0 and 2pi?

Yes, there are a few special cases to keep in mind when solving trig equations in this interval. These include when the equation has a coefficient in front of the trig function, when the equation is in terms of the cotangent function, and when the equation involves inverse trigonometric functions.

5. How can solving trig equations between 0 and 2pi be applied in real life?

Solving trig equations in this interval has practical applications in fields such as physics, engineering, and astronomy. For example, it can be used to calculate the position of an object in circular motion, the height of a building, or the trajectory of a projectile.

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