Question

I NEED HELP PLEASE, THANKS! :)

Answer 1

Answer:

Third option is the right choice.

Step-by-step explanation:

Manipulate the right hand side.

$\sec \left(x\right)\\\\=\frac{1}{\cos \left(x\right)}\\\\\mathrm{Use\:the\:following\:identity}:\quad \:1=\cos ^2\left(x\right)+\sin ^2\left(x\right)\\\\=\frac{\cos ^2\left(x\right)+\sin ^2\left(x\right)}{\cos \left(x\right)}\\\\\Rightarrow \mathrm{True}$

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Answer 2

Answer:

sin ^2 (x)+ cos^2(x)  = 1

Step-by-step explanation:

sin ^2 (x)+ cos^2(x)

------------------------

cos (x)

We know that  sin ^2 (x)+ cos^2(x)  = 1

1

------------------------

cos (x)

The definition of sec is 1 /cos

= sec(x)