February 23 - Scribe Post

Our warmup today involved taking a quizlet quiz on trig functions and the unit circle. We were allowed to use calculators and/or units circles, but BEWARE, because that opportunity will not be given on quiz day (Thursday!!)

We then moved into HW questions. There were a few questions from page 318 that were tricky...we worked them out in class. This homework should have been done Sunday, Monday, and Tuesday night, since vacation was supposed to be mathematics-free.

A few people were confused about 81 and 83. These involved finding an angle in radians and degrees given its sin, cos, etc. Ill give the example of 81:a...

81) a)
First, remember that sin represents the Y coordinate. Then, find the two places on the unit circle where the Y coordinate is positive one half. These happen to be 30 and 150 degrees.
Therefore, = 30 degrees, 150 degrees, radians, or radians.

Our main topic for the day was Trig Graphing. We started out with a demo on the Ferris Wheel site (linked in previous post). This shows how the relationship between and sine of on a coordinate plane creates a sinusoid wave. This is also known as the sine function.

There are two key geometric features of a sinusoid wave:
-Amplitude: the distance from the middle to the top or bottom of the wave.
-Period: the length of a cycle of the graph (one time around the unit circle).

Example:
, where the amplitude is the absolute value of , and the period is

The variation of these two factors transforms the graph. This is illustrated here: Transformations of the sinusoid wave

HW for today: Check out iCal, and don't forget to study your 198 trig values for the Q-U-I-Z next class.

The next scribe shall be Señor Murphy