Skip to content / Đến nội dung
ThichHocToan.com

MathNet 2014 Question 40

Math Olympiad Vault · MathNet 2014

Question 40

Does there exist a positive real number $a$ such that for every real $x$ the inequality
$$
|\cos x| + |\cos a x| \gt \sin x + \sin a x
$$
holds?