Question

Using the relation $2(1-\cos x)<x^2,x\ne 0$ or otherwise, prove that $\sin \left(\tan x\right)\ge x,\forall x\in [0,\frac{\pi }{4}]$

Answer 1

Given that 2(1−cosx)<x2,x≠02(1−cos⁡x)<x2,x≠0