Redefining a term in an equation

[abusementpark]

Hey guys,

I need to know to redefine a term in an equation. For instance, I have some equations defined that will yield expressions with sin(t) and cos(t) terms. I want to redefine these as sin(t)= y/sqrt(x^2+y^2) and cos(t)= x/sqrt(x^2+y^2), respectively. I am not really sure have to do this since sin(t) and cos(t) aren't variables.

Thanks.

 

[philipoakley]

An example file showing the expected context before and after would help.

You can use the live symbolics to do a substitute and carry the new equaation forward (often in a new holding variable such as "Eqn2=", then "Eqn3=", etc.)

The other option is a solve block with symbolic find which could take the x^2+y^2=z^2, etc. hence the need for a context to get the best choice.