1. First, we are going to find the value of
![x](https://img.qammunity.org/2019/formulas/mathematics/college/lhtxftojjkzsmo3o2h4ilq8naohracejui.png)
form April. We know form our problem that
the maximum afternoon temperature in month, x, with x = 0 representing January, x = 1 representing February, and so on; therefore:
January
![x=0](https://img.qammunity.org/2019/formulas/mathematics/high-school/9kvijf358dstmx6gyc4kvxfk183uebfiu1.png)
February
March
![x=2](https://img.qammunity.org/2019/formulas/mathematics/college/j2ylgqzlqmqlm551uh73cj4i3ylurdli25.png)
April
![x=3](https://img.qammunity.org/2019/formulas/mathematics/college/7ps1tadqt6n0r4c5twvavc795rj7e7v09l.png)
Now that we know that the value of
that represent April is 3, we just need to replace
with 3 in our model and evaluate:
![t=60-30cos( (x \pi )/(6) )](https://img.qammunity.org/2019/formulas/mathematics/high-school/jll22ffn2fmbfxx6w2mqseakkafd6t675l.png)
![t=60-30cos( (3 \pi )/(6) )](https://img.qammunity.org/2019/formulas/mathematics/high-school/xfsnageqf1k8uyv44v56zdsygsfbcweh8z.png)
![t=60-30(0)](https://img.qammunity.org/2019/formulas/mathematics/high-school/22su3lm3se2umij63bgzlfxbqfvhuiwdol.png)
![t=60](https://img.qammunity.org/2019/formulas/mathematics/high-school/ioq7j5jpsavv1hjnmuozdiep6txz10997i.png)
We can conclude that the maximum temperature in April will be 60.
2. Remember that in a function of the form
![y=C+Acos(Bx)](https://img.qammunity.org/2019/formulas/mathematics/high-school/j0f7jm5wfruqank58d9h258v6cu95mom98.png)
is the amplitude
is the vertical shift
We have tow option to change our model to increase the maximum temperature to global warming:
1. Increase the value of D to increase the vertical shifting of the model. D affects the maximum value of the function; if we increase D, the maximum value of the function will increase as well. We know from our model that
, so to increase the maximum temperature of our model, we just need to increase the value of 60.
2. Increase the value of A to increase the amplitude of the model. The amplitude, also increases or decreases the maximum value of the function -regardless of the sing of A, so if we increase the value of A, we will increase the value of the function. We know from our model that
, so to increase the maximum temperature of our model, we just need to increase 30 (without considering the sign).