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Right Triangles and Trigonometry Videos 37 videos
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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?
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.
Full Transcript
- 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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