Trigonometry

[ritwik06]

1. The problem statement, all variables and given/known data
Prove that:
\sqrt{3}cos 20 - sec 40=4


3. The attempt at a solution
Assuming th statement to be true;
\sqrt{3}cos 20 - \frac{1}{2cos^{2}20 - 1}=4

2\sqrt{3}cos^{3} 20- 8 cos^{2} 20 -\sqrt{3}cos 20+3=0

It results in a cubic equation???? Help

[Defennder]

Problem with this question is that it's not even true for both radians and degrees. Try it on your calc.

[Dick]

Problem with this question is that it's not even true for both radians and degrees. Try it on your calc.

That is an excellent point. I hadn't even thought to try it. Duh.

[ritwik06]

Sorry guys it was a type error!

[snipez90]

Eh, if that 0 was a theta, it looks solvable.

[Defennder]

Yeah, but it reads "prove that..." and not "solve..."