How would I go about solving ? All help is welcome.

Printable View

- November 20th 2010, 05:22 AMatreyyuTrig inequality?
How would I go about solving ? All help is welcome.

- November 20th 2010, 05:47 AMHallsofIvy
By THINKING, not using "formulas"!

You know that is**always less**than or equal to 1. You also know that powers of a number between 0 and 1 are always smaller than the number itself: if then .

Saying that an absolute value of a power of cos(x) is "greater than or equal to 1" is exactly the same as saying it is**equal**to 1. And so the power itself is equal to either 1 or -1. That can only happen when the base is 1 or -1. For what x is cos(x)= 1 or cos(x)= -1? - November 20th 2010, 05:56 AMAlso sprach Zarathustra
- November 20th 2010, 05:59 AMPlato
Actually there are more values of x than Prof Halls gave.

If then the given inequality holds.