Monday, April 21, 2014

BQ#4 - Unit T Concept 3

https://www.desmos.com/calculator/hjts26gwst
https://www.desmos.com/calculator/hjts26gwst
 A "normal" tangent graph goes uphill, whereas a "normal" cotangent graph goes downhill. This is due to the ASTC pattern for tangent and cotangent: positive (I), negative (II), positive (III), and negative (IV).  In the last unit, we learned about the ratio identities for tangent and cotangent: tanθ = sinθ/cosθ; cotθ = cosθ/sinθ.
Since asymptotes only exist when there is an undefined, in tangent, cos must equal 0Thus, cos=0 at 90 degrees and 270 degrees, which is (+)(-)pi/2. Thus, the formula to find the asymptotes for tangent would be b(x-h)= (+)(-)pi/2.
In cotangent, sin must equal 0.  Moreover, sin=0 at 0 degrees and 180 degrees, which is 0 or pi. Therefore, the equation to find the asymptotes for cotangent would be b(x-h)=0 or b(x-h)=pi.
Therefore, he only way for the graph to drawn according to the pattern and without crossing the asymptotes would be in an uphill graph for tangent, and downhill graph for cotangent. 

Saturday, April 19, 2014

BQ#3 – Unit T Concepts 1-3

How do the graphs of sine and cosine relate to each of the others?

a. Tangent
https://www.desmos.com/calculator/hjts26gwst
In the last unit, we learned about ratio identities. The ratio identity of tanθ = sinθ/cosθ. The asymptotes are where the graph is undefined, so cos would have to equal 0 for this to be true. Also, cos=0 at 90 degrees and 270 degrees, which is pos/neg pi/2. This is where the asymptotes are located. Moreover, when sine crosses the x axis, tangent does not because there is an asymptote. When cosine crosses the x-axis, there is another asymptote for tangent. A tangent graph is not continuous because there are asymptotes restricting it.

b. Cotangent
https://www.desmos.com/calculator/hjts26gwst
The ratio identity of cotθ = cosθ/sinθ. Therefore,in order for there to be asymptotes, sinθ must equal 0. Therefore, there are asymptotes at 0 degrees and 180 degrees, which is 0 and pi. Thus, similarly to tangent, the asymptotes for cotangent correspond to where sine and cosine cross the x axis. It is also not continuous.

c. Secant
https://www.desmos.com/calculator/hjts26gwst
In a secant graph, they form parabolas above the mountains and below the valleys of a cosine graph. Moreover, it is not continuous because there are asymptotes.

d. Cosecant
https://www.desmos.com/calculator/hjts26gwst

.A cosecant graph corresponds with a sine graph. A cosecant graph also forms parabolas like a secant graph, but this time they touch the mountains and valleys of a sine graph. This graph is also not continuous because of the asymptotes.

Friday, April 18, 2014

BQ#5 – Unit T Concepts 1-3

Why do sine and cosine not have asymptotes? Yet, the other four types of graphs do?


Asymptotes are where the graphs will equal undefined. In the case of sine and cosine, they both have "r" as a denominator (Please see chart above). And, since it is a unit circle, r=1. This makes it impossible for sine and cosine to be undefined, which explains why they do not have asymptotes.
Moreover, cosecant and cotangent have similar asymptotes because they both have the denominator of "y". The same appies to secant and tangent, which have the same denominator, "x".

Wednesday, April 16, 2014

BQ#2 – Unit T Concept Intro

How do the trig graphs relate to the Unit Circle?
a. Period?

In sine, the first and second quadrant are positive while the third and fourth quadrant are negative. If we were to unwrap the unit circle and graph it, the 1st and 2nd quadrant would be above the x axis (positive) and the 3rd and 4th quadrant would be below the x axis (negative). This means that for it to have a positive mountain and negative valley, the period must be 2pi because it goes all around the unit circle.Please look at the first picture for a visual.  Cosine is positive in the first and fourth quadrants and negative in the second and third. Cosine also follows the same rules. So, when it is positive, the graph is above the line and when it is negative, it is below the line. Please look at the 2nd picture for a visual. Therefore, it also takes 2pi to have a completed cycle. However, tangent and cotangent are positive in the first and third and negative in the second and fourth quadrant. When we graph this, we can see that it only takes 1pi to complete the cycle. Please see the third picture. 

b. Amplitude
Sine and Cosine graphs have amplitudes of 1 because a unit circle has a radius of 1. If we were to unravel a unit circle, and graph it according to the sin and cosine graph, the amplitudes would be 1. This works for only sine and cosine because they have bounded ranges, which means it has an upper limit and lower limit. The rest of the graphs do not have bounded ranges. They have infinity in the range. 

Friday, April 4, 2014

Reflection #1 - Unit Q: Verifying Trig Identities

1. Verifying a trig function means proving that the equation is true. When we do this, we can never touch the right side because it changes the original problem. It is our goal to make the left side equal the right side.

2. I have found it helpful to have all the identities (reciprocal, ratio, and Pythagorean) memorized so that it saves time. And, this allows me to recognized certain patterns and solve the equations faster. Moreover, I have found it useful to always look for a GCF because it can make an equation tremendously easier to work with.

3. When I verify a trig function, I always keep in mind what the answer is.  This can give me a hint to what I need to do in order to prove it. One of the first things I always do is check if I can pull out a GCF. When applicable, this greatly simplifies the equation.  Next, I check if I can change everything to sin and cos because these two trig functions are the easiest to work with and have ratio identities that may be used. Furthermore, if I see a binomial in the denominator, I try to use conjugates or LCD. If I see a binomial in the numerator, I check to see if separating the equation will help solve it. After determining the first step to take, I use the identities to further simplify the equation.  I have found that after determining the first step, the rest of the equation is fairly simple.  Just utilize the identities to their fullest potential and keep working even though it may look messy. Finally, always keeping the verification answer in mind can help you stay on the right track.