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Rita is proving that the following trigonometric identity is true:

cos(−θ)/sin(−θ)=−1/tanθ


Which step would be the first line of her proof?

 

A) cosθ /sin θ= −1/tan θ

 

B) cosθ /−sin θ= −1/ tanθ

 

C) cos(−θ) ⋅ tanθ = sin(−θ)

 

D) cos(−θ) / sinθ = −1/tanθ

 Nov 17, 2018
 #1
avatar+104666 
+2

Note  .... cos (-θ) = cos(θ)     and  sin (-θ)  =  -sin(θ)

 

So....the next step should be

 

cos(θ) / - sin (θ)  =  -1 / tan (θ)   ⇒  "B"

 

 

 

cool cool cool

 Nov 17, 2018

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