As was notedabove,this kind of data needsto be modeledwith a functionthat is periodic.In particular, this
kind of data is oftenmodeledby a sinusoid,a graphthat oscillatesin a particularway, as seenin the graph
below.
Everysinusoidrepeatsits valueson a regularinterval.If we modeledthe weatherdata with sucha graph,
the valueswill repeatevery12 months.Thereforewe say that the periodof the functionis 12.
Noticethat the data rangesfrom about22 to 65. Also noticethat the “wave”centersin betweenthesevalues,
aroundy= 43. Thereforewe say that the amplitudeof the waveis about21, whichis the distancefrom the
middleto the top or the bottomof the wave.
Manyreal phenomenacan be modeledwith this kind of function.
LessonSummary
In this lessonwe havereviewedthe conceptof a function,includingmajoraspectsof functions,and different
typesof functions.We havealso usedgraphingcalculatorsto graphand exploredifferentfunctions.A key
pointof this lessonis that we can use functionsto modelreal phenomena.A secondkey pointis that in order
to modelphenomenathat are cyclicalin nature,we needto use functionsthat are periodic.In lesson4 in