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Right Triangles and Trigonometry Videos 37 videos

Solving Trigonometric Equations
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Verifying Trig Identities
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Verifying trig identities is important, especially when you're about to let one of them into the country—which is why they should keep their pass...

Tangent Half-Angle Formula
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ACT Math 1.4 Trigonometry 254 Views


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Description:

ACT Math: Trigonometry Drill 1, Problem 4. Can you find the sine?

Language:
English Language

Transcript

00:02

For a good time, solve this shmoopy question...

00:05

Find the sine of the quantity pi over 4?

00:08

And here are the potential answers...

00:12

I'll looks like instead of degrees we're getting into radians

00:16

the angle measure made by wrapping the radius length around a circle

00:20

Just think of pi as a 180 degrees. How did we come up with that?

00:24

Well the formula for the circumference of a circle is 2

00:28

pi times the radius of the circle.

00:31

Well in a unit circle, that's where the radius is just 1,

00:34

we can describe a full 360 degrees of a circle as 2pi

00:39

times one or just 2pi radians

00:43

if 360 degrees is 2pi radians...half of 360 is 180 or

00:48

pi radians. Plug in 180 for pi

00:51

in sine over pi over 4... 180 divided by four is 45

00:55

Sine of 45 degrees is the square root of 2 over 2.

01:00

Option D is our answer.

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