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?

Guest Feb 14, 2018

edited by
Guest
Feb 14, 2018

#1**+1 **

Look at the secant graph here :

https://www.desmos.com/calculator/g2ulbffk6j

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 !!

CPhill
Feb 15, 2018

#2**+1 **

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

Mellie
Feb 15, 2018