Fundamental Math

IT100 Session 9: Trigonomic Functions
1 Nov 2017

Agenda

Agenda

  1. Your petition
  2. Solving Trigonometric Equations with Identities
  3. Sum and Difference Identities
  4. Double-Angle, Half-Angle, and Reduction Formulas
  5. Sum-to-Product and Product-to-Sum Formulas
  6. Solving Trigonometric Equations
  7. Modeling with Trigonometric Equations

Your petition

Initial Session

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Signatories

signatories

Petition

petition

Key issues

  • Teaching methods
  • The set up of the room
  • Computers are a distraction
  • Want to work with paper with pencil
  • ???

Agreed Class Goals

  • Pass this course
  • Supplement knowledge
  • Prepare for other courses
  • Assist in career suubjects
  • Solve difficult problems with ease
  • Able to explain math
  • Develop a love for math
  • Learn something new and practical

Class Rules

  • Help each other
  • Understand respect each other
  • Work collectively
  • Work on effective communications
  • Come ready to discuss the topic
  • Commitment to achieve goals

Some questions

  • Who is this petition addressed to?
  • What opinions/resources have you already explored?
  • What do you really want?

Unit Test Results

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Composite Grade

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Trigonometric Equations and Identities

Basic definitions

\[ \large\begin{array}{rrcll} cosine: & \cos\ \theta &=&{x \over r} & = {1\over\sec\ \theta}\\ sine: & \sin\ \theta &=&{y \over r} & = {1\over \csc\ \theta}\\\ tangent: & \tan\ \theta &=& {y \over x} & = {1\over \cot\ \theta}\\ secant: & \sec\ \theta &=& {r \over x} & = {1\over \cos\ \theta} \\ cosecant: &\csc\ \theta &=& {r \over y} & {1 \over \sin\ \theta}\\ cotangent: &\cot\ \theta &=& {y \over x}& {1 \over \tan\ \theta}\\ \end{array} \]

triangle

Identities

\[ \large\begin{array}{rcl} \sin\theta &=& \cos\left({\pi\over 2} - \theta\right) \\ \\ \cos\theta &=& \sin\left({\pi\over 2} - \theta\right) \\ \\ \tan\theta &=& \cot\left({\pi\over 2} - \theta\right) \\ \end{array} \]

Half-Angle, Double-Angle, and Reduction Formulas

Half angle formulas

\[ \large\begin{array}{rcl} \sin\left({\theta\over 2}\right) & = & \pm \sqrt{1- \cos(\theta)\over 2}\\ \\ \cos\left({\theta\over 2}\right) & = & \pm \sqrt{1 + \cos(\theta)\over 2}\\ \\ \tan\left({\theta\over 2}\right) & = & \pm \sqrt{1 - \cos(\theta)\over 1 + \cos(\theta)} = {\sin(\theta) \over 1 + cos(\theta)} = {1 - cos(\theta)\over \sin(\theta)}\\ \end{array} \]

Double angle formulas

\[ \large\begin{array}{rcl} \sin\left(2\theta\right) & = & 2 \sin(\theta) \cos(\theta)\\ \\ \cos\left(2\theta\right) & = & \cos^2(\theta) - \sin^2(\theta) = 1 - 2 \sin^2(\theta) = 2 \cos^2(\theta) - 1\\ \\ \tan\left(2\theta\right) & = & {2 \tan(\theta)\over 1 - \tan^2(\theta)} \\ \end{array} \]

Reduction Formula

\[ \large\begin{array}{rcl} \sin^2 \theta & = & {1 - \cos(2\theta)\over 2}\\ \\ \cos^2 \theta & = & {1 + \cos(2\theta)\over 2}\\ \\ \tan^2 \theta & = & {1 - \cos(2\theta)\over 1 + \cos(2\theta)}\\ \end{array} \]

Sum, Difference, Product

Sum Formulas

\[ \large\begin{array}{rcl} \sin(\alpha + \beta) & = & \sin\alpha \cos\beta + \cos\alpha \sin\beta\\ \\ \cos(\alpha + \beta) & = & \cos\alpha \cos\beta - \sin\alpha \sin\beta\\ \\ \tan(\alpha + \beta) & = & {\tan\alpha + \tan\beta\over 1 - \tan\alpha \tan\beta}\\ \end{array} \]

Difference Functions

Difference \[ \large\begin{array}{rcl} \sin(\alpha - \beta) & = & \sin\alpha \cos\beta - \cos\alpha \sin\beta\\ \\ \cos(\alpha - \beta) & = & \cos\alpha \cos\beta + \sin\alpha \sin\beta\\ \\ \tan(\alpha - \beta) & = & {\tan\alpha - \tan\beta\over 1 + \tan\alpha \tan\beta}\\ \end{array} \]

Product to Sum

\[ \large\begin{array}{rcl} \cos\alpha \cos \beta & = & {\cos(\alpha -\beta) + \cos(\alpha + \beta)\over 2}\\ \\ \sin\alpha \sin \beta & = & {\cos(\alpha -\beta) - \cos(\alpha + \beta)\over 2}\\ \\ \sin\alpha \cos \beta & = & {\sin(\alpha +\beta) + \sin(\alpha - \beta)\over 2}\\ \\ \cos\alpha \sin \beta & = & {\sin(\alpha +\beta) - \sin(\alpha - \beta)\over 2}\\ \end{array} \]

Law of Sines

\[ \large {\sin \alpha\over a} = {\sin \beta\over b} = {\sin \gamma \over c} \]

\[ \large {a \over \sin \alpha} = {b \over \sin \beta} = {c \over \sin \gamma} \]

triangle angles

Area of an oblique triangle

triangle angles

\[ \large Area = {bc\ \sin \alpha\over 2} = {ac\ \sin \beta\over 2} = {ab\ \sin \gamma\over 2} \]

Extra Credit Project 1

Loi Krathong, 3 Nov

  • record the flight path of 2 balloons over 2 mins
  • calculate the height and distance of the balloon
  • plot the data
  • submit a report
  • reasonable submissions will get 5 points

Loi Krathong

Requirements

  1. Create 2 soda straw sighting tubes with a plumb line
  2. Form a team of 5 student.
    • Timekeeper with a flashlight to signal teams
    • 2 sighters with the slighting tubes
    • 2 protractor readers with flashlights
  3. Separate slighting teams by 30 paces
  4. Use the flashlight to synchronize readings every 10 sec measuring
  5. Track the balloon for 2 mins

Sightingtube

Contents of the Report

  • Names and roles of team members
  • List the time and angle data collected for both teams
    • the angle between the ground and the balloon
    • the angle between the balloon and the other measuring team
  • List of the calculated distance and height
  • A plot of the flight path
  • Submit the report before class on 8 Nov

Calculations

blimp

  • Calculate missing angle:
    \( \large C = 180 - (70 + 60) = 50 \)
  • Calculate length of the Segment \( \large AC \):
    \( \large {AC \over \sin(60)} = {145\over \sin C} = {145\over \sin(50)} \)
  • Calculate height:
    \( \large ht = AC\ \sin(70) \)

Extra Credit Project 2

Innovation

Bungee chord challenge

  • Student teams of 2 or 3 experiment with 10 rubber bands
  • Create a linear mathematical model from the data
  • Predict the number of rubber bands needed to create a bungee chord
  • Test the performance of the bungee chord
  • The closest entry without hitting the ground wins a prize
  • Experimentation starts at 10AM, testing at 11AM

Report Contents

  • Names of the team member
  • Test data from experiments with 10 rubber bands
  • Plot of the stretch achieved for 1 to 10 bands
  • The linear model suggested by the data
  • Predicted number of rubber bands and the test results
  • A group picture of the team assembling the bungee chord
  • Printed submitted before class on 8 Nov
  • Worth 5 points of the course