Draw Angles & Find Values in Unit Circle

Click For Summary

Discussion Overview

The discussion revolves around drawing angles on the unit circle and finding the corresponding values of sine, cosine, tangent, and cotangent for specific angles. Participants explore methods for visual representation and seek tools to assist in this task.

Discussion Character

  • Exploratory, Technical explanation, Homework-related

Main Points Raised

  • One participant requests drawings for angles $\phi=\frac{\pi}{6}, \ \ \phi=\frac{\pi}{4}, \ \ \phi=\frac{2\pi}{3}, \ \ \phi=\frac{5\pi}{6}, \ \ \phi=-\frac{2\pi}{3}, \ \ \phi=-\frac{\pi}{3}$, along with their sine, cosine, tangent, and cotangent values.
  • Another participant suggests that separate drawings for each angle should be made, providing an example value of $\sin\frac\pi 6=\frac 12$.
  • A participant shares a link to an online interactive tool for trigonometric functions but notes it only displays one function at a time.
  • Suggestions for alternative tools include Desmos, Geogebra, and TikZ for creating the desired visualizations.
  • A participant provides a TikZ example from Stack Exchange, demonstrating how to draw angles and the unit circle, and shares a link to a TikZ Live Editor for editing the example.

Areas of Agreement / Disagreement

Participants generally agree on the need for separate drawings and the exploration of tools for visualizing trigonometric functions, but no consensus on a specific method or tool has been reached.

Contextual Notes

Participants express uncertainty about what it means to provide the four values explicitly and seek clarification on the requirements for their drawings.

mathmari
Gold Member
MHB
Messages
4,984
Reaction score
7
Hey! :giggle:

Make a drawing for each of the values of the angle below indicating the angle at the unit circle (in other words: $\text{exp} (i \phi )$) and its sine, show cosine, tangent and cotangent.

Give these four values explicitly in every case (you are allowed to use elementary geometry and the Pythagorean theorem).

$$\phi=\frac{\pi}{6}, \ \ \phi=\frac{\pi}{4}, \ \ \phi=\frac{2\pi}{3}, \ \ \phi=\frac{5\pi}{6}, \ \ \phi=-\frac{2\pi}{3}, \ \ \phi=-\frac{\pi}{3}$$

So at a unit circle we draw an angle $\phi$ and then we get a drawing like the following, right? But what does it mean to give these four values explicitly? :unsure:

1613497780785.png
 
Physics news on Phys.org
mathmari said:
So at a unit circle we draw an angle $\phi$ and then we get a drawing like the following, right? But what does it mean to give these four values explicitly? :unsure:
Hey mathmari!

Nice picture! (Sun)
I believe we're supposed to make a separate drawing for each of the angles, and give the corresponding values, such as $\sin\frac\pi 6=\frac 12$. 🤔
 
Klaas van Aarsen said:
I believe we're supposed to make a separate drawing for each of the angles, and give the corresponding values, such as $\sin\frac\pi 6=\frac 12$. 🤔

I have found an online interactive tool to show all the trigonometric functions : https://www.matheretter.de/rechner/trigonometrie

But this shows only one function at a time, do you maybe know if these is a similar tool that shows all trigonometric function in one picture?

:unsure:
 
mathmari said:
I have found an online interactive tool to show all the trigonometric functions : https://www.matheretter.de/rechner/trigonometrie

But this shows only one function at a time, do you maybe know if these is a similar tool that shows all trigonometric function in one picture?
Have you considered Desmos, Geogebra, or TikZ? 🤔
 
Klaas van Aarsen said:
Have you considered Desmos, Geogebra, or TikZ? 🤔

I tried now Desmos :

1613503760071.png
:unsure:
 
I found this TikZ example on stack exchange:
https://tex.stackexchange.com/quest...-and-tangent-to-calculate-coordinates-in-tikz
\begin{tikzpicture}
\usetikzlibrary{angles,quotes}
\tikzset{My Grid/.style={help lines,color=blue!50}}

\draw[My Grid] (-4,-4) grid (4,4);
\draw (-5,0) node[ left ] {$(-5,0)$} -- (5,0) node[ right ] {$(5,0)$};
\draw (0,-5) node[ below ] {$(0,-5)$} -- (0,5) node[ above ] {$(0,5)$};
\draw (0,0) circle [ radius=3cm ];

\coordinate(O)at(0,0);
\draw[red, very thick] (30:3cm)coordinate(A)
--({3*cos(30)},0)coordinate(B);

\draw [very thick,orange] (3,0) -- (3,{3*tan(30)})coordinate(C);
\pic[fill=green!50!black,
angle radius=0.75cm,
angle eccentricity=1.2,
"\(\alpha\)"] {angle=B--O--A};
\draw (O)--(C);
\end{tikzpicture}
Code:
\begin{tikzpicture}
\usetikzlibrary{angles,quotes}
\tikzset{My Grid/.style={help lines,color=blue!50}}

  \draw[My Grid] (-4,-4) grid (4,4);
  \draw (-5,0) node[ left ] {$(-5,0)$} -- (5,0) node[ right ] {$(5,0)$};
  \draw (0,-5) node[ below ] {$(0,-5)$} -- (0,5) node[ above ] {$(0,5)$};
  \draw (0,0)  circle [ radius=3cm ];

  \coordinate(O)at(0,0);
  \draw[red, very thick] (30:3cm)coordinate(A)
                         --({3*cos(30)},0)coordinate(B);

  \draw [very thick,orange] (3,0) -- (3,{3*tan(30)})coordinate(C);
  \pic[fill=green!50!black,
       angle radius=0.75cm,
       angle eccentricity=1.2,
       "\(\alpha\)"] {angle=B--O--A};
   \draw (O)--(C);
\end{tikzpicture}

We can edit it with the TikZ Live Editor:
https://tikzimages.mathhelpboards.com/tikz/tikzlive.html
 
Last edited:

Similar threads

  • · Replies 12 ·
Replies
12
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 4 ·
Replies
4
Views
1K
Replies
5
Views
3K
  • · Replies 157 ·
6
Replies
157
Views
12K
  • · Replies 21 ·
Replies
21
Views
3K
Replies
8
Views
3K
  • · Replies 14 ·
Replies
14
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K