Use the pythagorean theorem to find the pixel density of popular smartphones.

1. Name ________________________________
Date _________________________________
Pixel Density
You’re in the market for a new smartphone, but there are so many options – you can’t choose!
You want the best picture quality for streaming photos, taking pictures, and creeping on social
media sites. So, you’re looking for the highest pixel density!
What is pixel density?
Pixel density is the screen’s display resolution. The density is measure in pixels per inch, or ppi;
however, this does not indicate the number of pixels per square inch on the screen. Instead,
pixels per inch refers to the number of pixels per linear inch along the diagonal.
Why are we interested in pixels?
Pixels are the tiny dots of color on the screen of a tablet, smartphone, LCD TV, laptop, etc. The
more pixels a screen display has, the sharper the image. Compare these two photos: the first is an
iPhone 3, and the second is an iPhone 4 with retina display.

2. Directions: Calculate the pixel density for each smartphone, given the resolution dimensions in
pixels, and the length of the display in inches. Show your work.
Start with the iPhone 5:
Smartphone
Name
Length of the
display (inches)
Length of the
display (pixels)
Width of the
display (pixels)
Pixel Density

3. Now, try this for the remaining three smartphones.
Smartphone
Name
Length of the
display (inches)
Length of the
display (pixels)
Width of the
display (pixels)
Pixel Density

4. Consider the following questions for your reflection/rationale.
1. How does this information change the way you view mathematics? If your view does not
change, why not?
2. How does this information change the way you, as a consumer, think about and choose the
items you purchase?
3. Explain the steps to find the pixel density of a screen.
4. Why does the Pythagorean Theorem play a role in finding the pixel density?