Question

Solve for 0

(cos(t))^3)-1/(cos(t))^2

please help im desperate

Answer 1

Did you mean, given \[(cos(t))^3-{1\over(cos(t))^2}=0\]
solve for t?

Answer 2

Assuming you did then:

\[ cos^{3}(t)={1\over cos^{2}(t)}\]
\[cos^{5}(t)=1\]
\[t=cos^{-1}(\sqrt[5]{1})\]

This could be considered simply as \[t=cos^{-1}(1)\]
or you could consider the other roots of 1.... If that concept is unnecessary for your problem then you could just stick with the simple answer, but technically there are lots more solutions... http://en.wikipedia.org/wiki/Root_of_unity