[SPLIT] Find alg. expr. equiv. to cos(arcsin 2x)

[jonjon1324]

now I'm confused again It says:

Write an algebraic expression that is equivalent to the expression. (Hint: Sketch a right triangle): cos(arcsin 2x)

and in the back it says the answer is

all under a radical: 1 - 4x(squared)

 

[pka]

Study the diagram. You should be able to see what is going on.

 

[jonjon1324]

Study the diagram. You should be able to see what is going on.

I don't
I'm kinda bad at this.

 

[stapel]

Study the diagram. You should be able to see what is going on.

I don't I'm kinda bad at this.

It's not really a matter of being "good" or "bad" at looking at pictures. :shock:

It's pretty much just a matter of knowing what sines and cosines are, so that the picture makes any sense. So I'll ask again: Are you at all familiar with sines, cosines, and tangents? :idea:

Thank you!

Eliz.

 

[jonjon1324]

Yeah I do.
Okay wait I think I know what was done...since 1 is the hypotenuse, then to find the missing side i squared 1 and 2x and it ended up being 1-4x2...um..or something?
I guess

But now I'm confused again!
Well maybe not confused..just wanna see if I did this correctly.

sec(arctan 3x) = 9x2+1
is that right?

 

[Deleted member 4993]

Yeah I do.
Okay wait I think I know what was done...since 1 is the hypotenuse, then to find the missing side i squared 1 and 2x and it ended up being 1-4x2...um..or something?
I guess

But now I'm confused again!
Well maybe not confused..just wanna see if I did this correctly.

sec(arctan 3x) = 9x2+1 <--- Please show your work for us to comment
is that right?

 

[jonjon1324]

Yeah I do.
Okay wait I think I know what was done...since 1 is the hypotenuse, then to find the missing side i squared 1 and 2x and it ended up being 1-4x2...um..or something?
I guess

But now I'm confused again!
Well maybe not confused..just wanna see if I did this correctly.

sec(arctan 3x) = 9x2+1 <--- Please show your work for us to comment
is that right?

Well I..um okay I don't know how to explain this on the internet.

 

[stapel]

I don't know how to explain this on the internet.

How would the spoken words and written steps differ, "on the Internet", from what you would do for your homework? :shock:

Eliz.