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Trig question help. Please explain. I think the answer is supposed to be -1 but how do you know that it cannot be the other choices?

 Feb 14, 2018
edited by Guest  Feb 14, 2018

Look at the secant graph here :




Note  that  the range  is   ( - inf, -1 ] U [ 1, inf )


So.....the secant's  range  always has an absolute value   ≥  1


Only the first answer  meets that criteria....so....you are correct  !!



cool cool cool

 Feb 15, 2018

We know that sec(x) is equal to cos(x) because it is the reciprocal of cosine.


So, choice d cannot be correct because cos(x) cannot be 0, because it would result in an undefined answer. 


We we know that cosine is adjacent/ hypotenuse. Of course, the reciprocal would be hypotenuse/adjacent. 


If if you look at choice b, c, and e, the numerators (hypotenuse) are all smaller than the denominator (adjacent side). This is not possible because the hypotenuse in a triangle cannot be less than one side. 


this is why choice A must be correct

 Feb 15, 2018

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