− 2 p −p p 2 p q1− 10cos q(^22)
p p 3 p
2
3 p
−− 2
Figure 6.9cosθ − 2 π≤θ≤ 2 π.
−p 0 p 3 p p 5 p q
1
− 1
tan q
4
p
2 4 4
3 p
2
3 p
− 2
5 p
− 4
3 p
− 4
p
− 2
p
− 4
Figure 6.10tanθ −
3 π
2
≤θ≤
3 π
2
.
Trig functions are very often used in describing time varying wave-like behaviour, where
a typical functional form might be thesinusoidal functionoft:
y=Asin(ωt+α)
Such a wave-like graph is called asine wave(whether it is cos or sin).Ais called
theamplitudeof the wave, 2π/ωitsperiod, since it repeats after this cycle,ω/2 its
frequencyandαitsphase. This terminology is standard in the theory of waves in science
and engineering. The solutions to the review question provide a number of examples.