If the number of concerts held in a city is correlated to the number of local radio channels, what third variable might most likely be responsible for this correlation?
the number of songs played on each channel
the weather conditions of the city
the number of music lovers in the city
the duration of each concert
the correct answer is option d : 120°
first we bring all the cos x terms to one side
2 = 5 + 6 cos x
now we bring all the numerals to one side
-3 = 6 cos x
- = cos x
∵ cos 60° = ∴ cos x = cos 60°
x = 60°
now just flip over for the negative to get 180-60 = 120
∴ the answer is 120°.
options a and b
amplitude of the graph = 3 but shown correctly
hence option a is right
there is a vertical shift of 1/2 down. shown correctly
option b is right
horizontal shift is 1 unit to the left after adjusting x for x/4. shown incorrectly
option c is not right
period is 8 pi not shown correctly
option d is wrong.
horizontal expansion is not shown at all for x/4
hence option e is wrong.