Answer:
Step-by-step explanation:
Let's start with the simple ones:
a = amplitude = (highest - lowest) divided by 2 = (11-1)/2 = 5
d = offset = (highest + lowest) divided by 2 = (11+1)/2 = 6
Now, if x goes 'untreated', the cos would make a full swing after 2pi.
Here, it repeats after 3. To achieve that, we divide by 3 and multiply by 2pi.
b = 2pi/3
You can try it out (assuming c=0 for a minute): x=3 puts bx at 2pi.
Now for the final one, the shift left by one. We cannot say c=1 because that would be a 1 on the 2pi scale.
Rather, the shift would be c'=1 if the formula were acos(b(x+c')).
If we work out the parenthesis with c'=1, we get bx + b, so the actual c is 2pi/3