Which transformation causes the described change in the graph of the function y = cos x? the transformation results in a horizontal shrink. the transformation results in a vertical stretch. the transformation results in a horizontal stretch. the transformation results in a vertical shrink.

First lets look at our graph of y = cos x
***First picture***

Next lets look at a vertical stretch.
***Second picture***

To vertically stretch y = cos x, we need to multiply cos by a number greater than 1. I am going to use 2.

Standard Form: y = cos x (Red Line)
Vertical Stretch: y = 2 cos x (Blue Line)

Lets look at a vertical shrink
***Third picture***

To create a vertical shrink, you multiply the cos by a number less than 1. I am going to use .5

Standard Form: y = cos x (Red Line)
Vertical Shrink: y = .5 cos x (Green Line)

Now lets look at horizontal stretch.
***Forth picture.***

To create a horizontal stretch, you multiply the x by a value less than 1. I am going to use .5

Standard Form: y = cos x (Red Line)
Vertical Stretch: y = .5 cos x (Orange Line)

Finally, to create a horizontal shrink, you multiply the x by a value greater than 1. I am going to use 2.
***Fifth picture.***

Standard Form: y = cos x (Red Line)
Vertical Shrink: y = 2 cos x (Purple Line)

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The first one, i believe, would be correct. all the others have one thing in common, and that's that they have repeating numbers. in the second one, x and y have repeating 6's and 3's, and in the third, x and y have repeating 6's as well. in the last one, there are repeating 3's. the first one has no repeating numbers.