Parametics and conics... (1 Viewer)

[Michaelmoo]

Ok. So I'm on question 5, exercise 3.3 from cambridge. Looking at the solutions, I can't see how they get this:

asec@ - acos@ = acos@tan^2@

Is there a rule/theorem I havn't touched on?

Thanks.

 

[azureus88]

not really, its just:

asec@ - acos@
=acos@(sec^2@ - 1)
=acos@tan^2@

 

[Michaelmoo]

not really, its just:

asec@ - acos@
=acos@(sec^2@ - 1)
=acos@tan^2@

O i c. Never done sumin like that before.

Thanks.