Question

which expression is equivalent to (cos x) (tan(-x))

Answer 1

Hey!
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`which expression`
Do you have some options for us to look at?

Answer 2

Recall that `tangent is an odd function`.
Therefore \(\Large\rm \tan(-x)=-\tan x\)

Answer 3

\[\Large\rm \cos x \tan(-x)=-\cos x \tan x\]

Answer 4

Then recall your tangent identity,\[ \Large\rm \tan x=\frac{\sin x}{\cos x}\]

Answer 5

You should be able to simplify things with that information.
Understand how to proceed?

Answer 6

tan is sin/cos

giving sin^2 / cos + cos
now get common denoms

sin2/cos + cos2/cos

sin2 + cos2 = 1

so you're left w/

1/cos = sec

Answer 7

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