Question

I NEED HELP PLEASE, THANKS! :)

Answer 1

Third option is the right choice.

Explanation:

Manipulate the right hand side.

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

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Answer 2

sin ^2 (x)+ cos^2(x) = 1

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)