SOLUTION
Let us make a diagram of the computer screen, note that it is in the shape of a rectangle
From the diagram above, the diagonal is given as d, and that is what we want to find.
We can see that a right-triangle has been made, with sides 16, 12 and d.
To find d, we will make use of the Pythagorean theory.
According to this theory,
![\text{hypotenuse}^2=opposite^2+adjacent^2](https://img.qammunity.org/2023/formulas/mathematics/college/vcz72e68w7hh27znad96ghbshnsotp7cx2.png)
The hypotenuse here is the side d, applying this we have
![\begin{gathered} \text{hypotenuse}^2=opposite^2+adjacent^2 \\ d^2=12^2+16^2 \\ d^2=144+256 \\ d^2=400 \\ \text{square root both sides } \\ \sqrt[]{d^2}=\sqrt[]{400} \\ \text{square cancels square-root} \\ d=\sqrt[]{400} \\ d=20 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/hjo00n9v27i6wcnr9a8gm3yf2mhpjtfwyw.png)
Hence the answer is 20 inches