Unit circle problems (ive wikied and googled)

[ndmp]

Homework Statement

sin3x=.966 then x could be equal to (answer in degrees)

Homework Equations

solving trigonometric equations

The Attempt at a Solution

sin3x=3sinx
3sinx=.966
sinx=.966/3
sinx=.322
cos^2x + sin^2x=1 (pythagorean theory)
cos^2x +.322^2=1
1-.322^2=cos^2x
lol i get stuck i don't even know if I am on the right track.

 

[cristo]

Does sin(3x) equal 3*sin(x)?

 

[ndmp]

Does sin(3x) equal 3*sin(x)?

no that has not been proven, its just a track i thought i could go down. The only information that has been given was in step 1. Are u allowed to say that sin(3x) = 3 sin(x) is that a proven law?

 

[ndmp]

thanks for your help i have been trawling wikis and googling just to get a worked example... And i won't be able to sleep if i can't figure it out lol :P

It might help i know that the answer to sin3x=.966, that x =25 degrees, i just don't know how to prove it

 

[cristo]

For starters, the question in your post doesn't sound like it is the exact question you are asked to solve. Perhaps it will help if you copy verbatim.

Still, no, it is not true that sin(3x)=3sin(x). The way I would solve your problem would be to simply take the inverse sine of each side of your equation.

 

[ndmp]

For starters, the question in your post doesn't sound like it is the exact question you are asked to solve. Perhaps it will help if you copy verbatim.

Still, no, it is not true that sin(3x)=3sin(x). The way I would solve your problem would be to simply take the inverse sine of each side of your equation.

that was the question unfortunately, it had a multiple choice aspect :(. with 5 different degree answers.

So 3x = asin .966
3x=75
x=25 thanks so much :PPPPPP