Sign up ×
Mathematics Stack Exchange is a question and answer site for people studying math at any level and professionals in related fields. It's 100% free, no registration required.

So if I have an equation for a torus in $F(a,b) = (X, Y, Z)$ where $X = (R + r\cos a)\cos b$ and $0 < r < R$, how would I go about rewriting this equation for $X$ in terms of $\tan(a/2)$ and $\tan(b/2)$? I'm having a hard time doing the conversion. This might seem like an odd question but it's just the first step to a larger problem I'm working on but once I got this I'm good to go.

share|cite|improve this question
Are $x$, $y$ and $z$ functions of $a$ and $b$? Is $X$ the same as $x$? – Fly by Night Feb 23 '13 at 18:46
Sorry I should have been more clear in my notation. x and X are the same. My question boils down to simply rewriting the equation X = (R+rcosa)cosb in terms of tan(a/2) and tan(b/2) instead of cosa and cosb or just in some form that incorporates those tangents – user1855952 Feb 23 '13 at 18:48

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Browse other questions tagged or ask your own question.