Mi_Ka_

Yes, arccos(1/3) = 70.5287794 degrees

thanks a lot for sharing these links. Specially this one- http://fermatslasttheorem.blogspot.com/2005/08/another-false...

I understand, I need to prove that- cos θ is irrational for all θ, where 60<θ<90. Which is not actually true.

That is what I knew. For example- cos 75 = (√2(√3 – 1))/4

For testing you can visit here- http://www.webconversiononline.com/trigonometry-calculator.a...