Question 173031
3) the expression 
sin^2 x + cos^2 x / cos x 
is equivalent to 
1) sin x 2) cos x 3) sec x 4) csc x 
sin^2 + cos^2 = 1 (a basic identity.  Do you need proof of it?)
sin^2 x + cos^2 x / cos x = 1/cos = secant(x)
3) sec(x)
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4) if the probability that an event will occus is x/y , what is the probability that it will not occur?
1) y/x 2) -x/y 3) y - x / y 4) 1 - x / y 
All probabilities total 100%, or 1.
So the probability it will not occur = 1 - x/y
4) 1 - (x/y)