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ACT Math Videos 164 videos
ACT Math: Trigonometry Drill 1, Problem 1. What is the length of y?
ACT Math: Coordinate Geometry Drill 1, Problem 2. Solve the inequality and determine which solution is shown on the number line.
ACT Math 1.4 Trigonometry 254 Views
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Description:
ACT Math: Trigonometry Drill 1, Problem 4. Can you find the sine?
- Trigonometry / Trig identities
- Trigonometry / SOHCAHTOA (values and properties of trig functions)
- Product Type / ACT Math
- Foreign Language / Arabic Subtitled
- Foreign Language / Korean Subtitled
- Foreign Language / Chinese Subtitled
- Foreign Language / Spanish Subtitled
- Functions / Extend the domain of trigonometric functions using the unit circle
- Functions / Extend the domain of trigonometric functions using the unit circle
- Trigonometry / Solving trigonometric equations
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
Full Transcript
- 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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