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ACT Math 4.2 Trigonometry 203 Views


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Description:

ACT Math: Trigonometry; Drill 4, Problem 2. Which equation matches this graph?

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Transcript

00:02

Here's your shmoop du jour...

00:04

Which equation matches this graph?

00:06

Here are the choices...

00:11

First of all, it seems like we have a cosine graph...

00:13

It's cut unevenly by the x axis.

00:16

The bottom part of the graph only seems to go down to negative 1, while

00:20

the top parts reach all the way up to positive 3.

00:23

A normal cosine graph goes up and down in even amounts relative to the x-axis, which

00:28

means that this one is lifted up by 1...

00:31

...in other words, if we bring the graph down by 1, it will reach both 2 and negative 2.

00:36

The "lift" is represented by a "plus 1" which leaves only

00:39

answer choices D and E in the running.

00:41

place that pesky 2 -- before or inside of the parentheses?

00:41

We know that anything inside the parentheses modifies the period of the graph, or how tightly

00:46

the waves of the graph cycle. A normal cosine graph completes a full cycle

00:51

in 2π, and our cosine graph does the same, so it was not modified.

00:56

That means the 2 can't be in the parentheses but rather before the cos -- answer E.

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