pls teach me how to graph cosine function (even to the specific points)?

Answer 1

Make up a table where y = cos x :-
x *****0*** 30*** 60** 90* 120** 150**** 180
y***** 1* 0.866**0.5**0**- 0.5*- 0.866 **-1

x*******210***** 240*** 270** 300* 330** 360
y*****- 0.866**- 0.5*****0****0.5***0.866**1

x axis is horizontal
y axis is vertical

y values lie between - 1 and 1
x values go up in steps of 30 from 0 to 360.

Hopefully you can now plot points to obtain a smooth cosine graph.
Good luck!

Answer 2

If you have Excel you can do it in that very easily. By hand takes a little effort. Construct a table of values to start:

angle
-----------------------------
radians degrees Cos(x)
----------- -------------- ------------------------------
0 0 1
pi/6 30 SQRT(3)/2 = 0.866
pi/4 45 SQRT(2)/2 = 0.707
pi/3 60 0.5
pi/2 90 0
2pi/3 120 -0.5
3pi/4 135 -SQRT(2)/2 = -0.707
5pi/6 150 -SQRT(3)/2 = -0.866
pi 180 -1

New to this. It doesn't seem to likes spaces. When I look at these they are in columns but in preview they are not. Don't know how you will see them Don't know what to do about that if yours do not come out on columns.

Not a lot of points there but plot them and draw a smooth curve through them. 1 and -1 being the max and min of the cosine.

Answer 3

To see these equations, please copy paste the lines starting from \[ and ending in \] into the online form at http://www.tlhiv.org/cgi-bin/LaTeXpreviewer/index.cgi and hit 'Preview'

\[
\cos(0) = 1
\]
\[
\cos(\frac{\pi}{2}) = 0
\]
\[
\cos(\frac{\pi}{3}) = 1/2
\]

Begin plotting the points and draw a curved line through these points. That is a good enough approximate. Once you reach pi/2, turn the paper the other way and now plot those same points, considering for the moment, that pi is in the place of 0.

This way you will get a mirror-image of the first part of the plot. Repeat this process till you reach 2pi and then, it is a matter of replication.