If α is an acute angle, which of the following options will NOT necessarily be equal to the value of cosec α?

$\frac{1}{cos α}$

We know,

cosec α = \(\frac{1}{cosα}\)

And

cosec² α  - cot² α = 1

cosec² α = 1 + cot² α

cosec α = \(\sqrt {  1 + cot² α }\)

And ,

cosec α = \(\frac{1}{sinα}\)

multiply and divide by cosα .

sec α = \(\frac{1}{sinα}\) × \(\frac{cosα}{cosα}\) 

= \(\frac{cotα}{cosα}\)

But 

cosecα  ≠ \(\frac{1}{cosα}\)