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ACT Math 4.4 Trigonometry 204 Views


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Description:

ACT Math: Trigonometry Drill 4, Problem 4. What is the equation of the graph in the video?

Language:
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Transcript

00:02

For a good time, solve this shmoopy question.

00:05

If the cosine X equals root 2 over 2 ,what is the measure of angle x?

00:10

And here are the choices.

00:14

Okay, we know that cosine measures the adjacent side

00:17

over the hypotenuse. So we can figure out the triangle look something like this.

00:22

First we should find out length of the final side

00:26

by using the Pythagorean Theorem - A sqaured plus B squared equals C squared

00:29

we can determine that root 2 squared plus

00:32

X squared equals 2 squared. That's 2 plus x squared equals 4...

00:36

Subtract 2 from both sides and X squared equals 2.

00:40

Take the square root of both sides and X equals the square root of 2.

00:43

Awesome. That means we have an isosceles triangle where two sides are equal

00:47

better yet when two sides are equal that means that 2

00:50

angles are equal. Even better we already know that one angle is 90 degrees

00:55

since the triangle is a right triangle, which means

00:59

that the other two angles have to measure 45 degrees each

01:02

and we have our answer it's C.

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