Astronomers have observed that sunspots vary
sinusoidally. The variation is from a minimum of 40
sunspots per year to a maximum of about 200 per year. A
cycle last about 18 years. If a minimum occurred in 1974,
which function could model the number of sunspots, S, as
a filinction of a year, t?
S(x) = -80 cos (F (t - 1974)) + 120
O
S(x) = -120 cos ("
(t-1974)) +80
5(x) = -80 cos (2 (t - 1974) + 120
O
5(x) = -120 cos (:
- (+ - 1974))
+ 80