Which of the following statements relating to abc is false

The correct answer is:  [C]:  " cos A =  " .
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Note the mnemonic device:  "SOH CAH TOA" ; 

in which:  "sin = opposite/ hypotenuse" ; 
               
                 "cos = adjacent/ hypotenuse" ; 
             
                 "tan = opposite/ adjacent" .
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So, the "cos A" (that is, the "cosine" of "measure of angle, "A", should be equal the adjacent side length, "b" (in this diagram), divided by the hypotenuse length, "c" (in this diagram) .
   In other words, refers to "CAH" in the mnemonic:  "SOH CAH TOA" .
   "cos = adjacent/ hypotenuse". 

The statement in "Answer choice: [C]:  " cos A =  " ; is incorrect —and as such; the correct answer.
   "a / c " ; that is, the "opposite divided the hypotenuse" (with respect to "Angle A") ;  would be the "sin of Angle A".  

The correct statement for "cos A" is "cos A = b /c " (adjacent/hypotenuse).
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