MaplePrimes - answers and comments on Question, How do I tell Maple trig identities and make it remember

You can use the command

hirnyk — Mon, 08 Mar 2010 15:26:15 Z

You can use the command >simplify(expression,{sin(x)^2+cos(x)^2=1});

More trouble - Weird Lines

james_is_stuck — Mon, 08 Mar 2010 15:55:00 Z

[ posting edited to change Input format to Filtered HTML instead of Plain Text]

Thanks

But I'm still having trouble, I think it might be to do with these lines above some of the sines and cosines. I have no idea what they are.

Here's my input and output;

Xs:=Vector(3,[diff(X[1],s),diff(X[2],s),diff(X[3],s)]);
                       Vector[column](%id = 136901428)
Xt:=Vector(3,[diff(X[1],t),diff(X[2],t),diff(X[3],t)]);
                       Vector[column](%id = 136946480)
E:=Xs.Xs;
_____________                 _____________                    / __\
cos(s) cos(t) cos(s) cos(t) + cos(s) sin(t) cos(s) sin(t) + sin\s/ sin(s)

E:=simplify(E,{sin(t)^2+cos(t)^2=1});
/_\ /_\ /_\ /_\ /_\
cos\s/ cos\t/ cos(s) cos(t) + cos\s/ sin\t/ cos(s) sin(t) + sin\s/ sin(s)

Nonsense

james_is_stuck — Mon, 08 Mar 2010 16:07:38 Z

Ok, that didn't format as i meant it too, i'll try again later

It is difficult to answer

hirnyk — Mon, 08 Mar 2010 16:10:36 Z

It is difficult to answer your question as the code is unreadable. Input it by my files.

Example

james_is_stuck — Mon, 08 Mar 2010 17:52:01 Z

>	*X:=Vector(3,[sin(s)cos(t),sin(s)sin(t),cos(s)]);*

(1)

>	Xs:=Vector(3,[diff(X[1],s),diff(X[2],s),diff(X[3],s)]);

(2)

>	Xt:=Vector(3,[diff(X[1],t),diff(X[2],t),diff(X[3],t)]);

(3)

>	E:=Xs.Xs;

(4)

>	E:=simplify(E,{sin(t)^2+cos(t)^2=1});

(5)

complex conjugates

Tim Vrablik — Mon, 08 Mar 2010 21:59:43 Z

The bars that you are getting overtop of the sin/cos denote complex conjugates. For your particular question, you can just do E:=simplify(E, assume=real) and you'll get the result you are looking for.