# Lesson 16

When Is the Same Size Not the Same Size?

• Let’s figure out how aspect ratio affects screen area.

### 16.1: Three Figures

How are these shapes the same? How are they different?

### 16.2: A $4:3$ Rectangle

A typical aspect ratio for photos is $$4:3$$. Here’s a rectangle with a $$4:3$$ aspect ratio.

1. What does it mean that the aspect ratio is $$4:3$$? Mark up the diagram to show what that means.
2. If the shorter side of the rectangle measures 15 inches:
1. What is the length of the longer side?
2. What is the length of the rectangle’s diagonal?
3. If the diagonal of the $$4:3$$ rectangle measures 10 inches, how long are its sides?
4. If the diagonal of the $$4:3$$ rectangle measures 6 inches, how long are its sides?

### 16.3: The Screen Is the Same Size . . . Or Is It?

Before 2017, a smart phone manufacturer’s phones had a diagonal length of 5.8 inches and an aspect ratio of $$16:9$$. In 2017, they released a new phone that also had a 5.8-inch diagonal length, but an aspect ratio of $$18.5:9$$. Some customers complained that the new phones had a smaller screen. Were they correct? If so, how much smaller was the new screen compared to the old screen?