Solving Geometry Equations with Cosine and Euler Angles

[Hollysmoke]

in the textbook it says cos^2x + cos^2y + cos^2z=1 . How do we do cos^2?

 

[d_leet]

in the textbook it says cos^2x + cos^2y + cos^2z=1 . How do we do cos^2?

What do you mean "How do we do cos^2" ? I don't understand the question that you're asking, could you elaborate a little bit?

 

[Hollysmoke]

hmm...like, how do they get =1? What would I type into hte calculator to get that? The textbook wasn't very helpful in that sense.

 

[d_leet]

hmm...like, how do they get =1? What would I type into hte calculator to get that? The textbook wasn't very helpful in that sense.

Well it certainly isn't an identity. What is this in the context of, I mean how is this presented in the book? Is it a problem or what?

 

[Hollysmoke]

That's all it says. I'll ask the teacher tomorrow to elaborate and get back to you.

 

[d_leet]

That's all it says. I'll ask the teacher tomorrow to elaborate and get back to you.

But is this a problem, or just something like in an example or diagram? I'm sorry I couldn't be more help, it's just it's a very vague statement that I'm having a hard time inferring things from.

 

[Hollysmoke]

It's the equation that is given.

 

[d_leet]

It's the equation that is given.

And it says nothing else, no conditions or what the equation is supposed to be or be used for? I just have a hard time believing that something like this would be put in a textbook without any explanation if you are supposed to be learning it.

 

[topsquark]

What do you mean "How do we do cos^2" ? I don't understand the question that you're asking, could you elaborate a little bit?

Could x, y, and z be Euler angles? That's the only relationship I know of that looks like that.

-Dan

 

[HallsofIvy]

That's was my first thought: L is a line in 3 dimensions and x, y, z are the "Euler angles", the angles L makes with the x, y, z axes respectively. In that case, it must be the case that cos² x+ cos² y+ cos² z= 1. In fact, (cos x)i+ (cos y)j+ (cos z)k is a unit vector pointing in the direction of line L.

But Hollysmoke's question was how to enter the numbers into the calculator!

Hollysmoke, we really can't answer that without knowing what kind of calculator you are using. Different types of calculator require different kinds of entry. Also what are your values for x, y, z?