How to Solve Trigonometric Equation sin2x = sqrt(2)/2 Using Algebra?

In summary, a trigonometric equation is an equation that involves the use of trigonometric functions to solve for unknown angles or sides in a triangle or represent periodic phenomena. To solve these equations, the trigonometric function must be isolated and then simplified using inverse trigonometric functions or trigonometric identities. Some common identities used include Pythagorean, double angle, half angle, and sum and difference identities. There are also special cases to consider when solving these equations, such as different periods or multiple solutions. In real life, trigonometric equations are used in various fields to model and analyze periodic phenomena and solve problems involving angles and distances.
  • #1
manish00333
2
0
Solve sin2x= sqrt(2)/2 (using algebra)
the interval is between 0 and 2pi

i got the first two answers: pi/8 and 3pi/8, but i don t understand how to get the other two: 9pi/8 and 11pi/8.

thanks!
 
Last edited:
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  • #2
If we are told:

\(\displaystyle 0\le x<2\pi\)

then:

\(\displaystyle 0\le 2x<4\pi\)
 
  • #3
Oh, that makes sense!

So, pi/4 + 2pi = 9pi/4
and 3pi/4 + 2pi = 11pi/4

and when i divide them by 2, i get 9pi/8 and 11pi/8.

thank you so much! :D
 
  • #4
manish00333 said:
So, pi/4 + 2pi = 9pi/4
and 3pi/4 + 2pi = 11pi/4

and when i divide them by 2, i get 9pi/8 and 11pi/8.

Perfect! (Yes)
 

1. What is a trigonometric equation?

A trigonometric equation is an equation that involves the use of trigonometric functions such as sine, cosine, tangent, etc. These equations are used to solve for unknown angles or sides in a triangle, or to represent periodic phenomena in mathematics and science.

2. How do you solve a trigonometric equation?

To solve a trigonometric equation, you must first isolate the trigonometric function on one side of the equation. Then, use inverse trigonometric functions or trigonometric identities to simplify the equation and solve for the unknown variable.

3. What are some common trigonometric identities used in solving equations?

Some common trigonometric identities used in solving equations include the Pythagorean identities, double angle identities, half angle identities, and sum and difference identities. These identities allow you to rewrite trigonometric functions in terms of other functions to simplify equations.

4. Are there any special cases when solving trigonometric equations?

Yes, there are special cases when solving trigonometric equations, such as when the equation involves trigonometric functions with different periods or when solving for multiple solutions. In these cases, it is important to use the appropriate trigonometric identities and consider all possible solutions.

5. How are trigonometric equations used in real life?

Trigonometric equations have many practical applications in fields such as physics, engineering, and navigation. They are used to model and analyze periodic phenomena, such as sound waves and alternating currents, and to solve problems involving angles and distances in real-world situations.

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