Which of the following statement is(are) true or false:

(i) $\tan^{-1}(1)=\frac{π}{4}$

(ii) $\sin^{-1}\frac{π}{2}$ not defined

(iii) $\tan^{-1}x=\cot^{-1}\frac{1}{x}$

(iv) $cosec^{-1}x=\sin^{-1}\frac{1}{x},|x|≥1$

TTFT

(i) $\tan^{-1}(1)=\frac{π}{4}$ is true

(ii) $\sin^{-1}(1.57)$ = not defined ($\sin^{-1}x$ defined when -1 ≤ x ≤ 1) ⇒ The given equation is true

(iii) $\tan^{-1}x=\cot^{-1}\frac{1}{x}$ not true for all x

(iv) Standard result