## Tuesday, March 11, 2008

### Pre-Transformations Test Review

Hello everyone, it's Nelsa again, writing my second scribe post. Oh and, if anyone's confused, my nickname's Dimple, so uhm, that's that.

Most of this class was a review, since everyone's BOB posts contained uncertainties with graphing reciprocal functions and solving word problems like the one we just learned yesterday. We were placed into groups, and we started by solving the homework that everyone should have attempted for homework. I believe that is on the first four slides, not including the title.. page. Just remember guys, that wherever the function has roots, that's where the asymptote is, and the invariant points are where one and negative one is. Mark these first on your graph, it'll make things easier. From that point on, you just need to remember that whenever the values are smallering, the reciprocal is biggering, and whenever the values are biggering the reciprocals are smallering. Also, pay attention to the end points and arrows on a graph. If you draw an arrow when the graph clearly stops, you'll lose a full mark.

After reviewing our homework, we were given another word problem:

The pedals on a bicycle have a maximum height of 30 cm above the ground and a minimum distance of 8 cm above the ground. Jeng pedals at 20 cycles/minute.

The first question asked us to find the period in seconds. Since there's 20 cycles/minute, with each minute containing 60 seconds, we divided 60 by 20 to get 3 seconds/cycle. We were also asked to write two equations, which means figuring out ABCD. The sinusoidal axis. is the value between the minimum and the maximum (8 and 30), which is 19. The amplitude was found by subtracting 19 from 30, which is 11. The period as we know is 3, which means in the equation, the period is written as 2pi/3. All that was left to figure out was the phase shift, and after some confusions and disagreements, we finally agreed that for the cosine function, there was no phase shift, and for the sine function, the graph shifted to the right by 3/4. We found two equations using the above information.

And that was basically the whole class. Don't forget that we have a pre-test and a test tomorrow, good luck all. The next scribe shall be Kristina. =)