Whew. Experimenting with the angles requires you to change three different places in the code each time. Imagine you’d want to experiment with all of the square sizes, let alone with rectangles! We can do better than that.

This is where **variables** come into play: You can tell Python that from now on,
whenever you refer to a variable, you actually mean something else. That concept
might be familiar from symbolic maths, where you would write: *Let x be 5.*
Then *x * 2* will obviously be *10*.

In Python syntax, that very statement translates to:

```
x = 5
```

After that statement, if you do `print(x)`

, it will actually output its value
— 5. Well, can use that for your turtle too:

```
turtle.forward(x)
```

Variables can store all sorts of things, not just numbers. A typical
other thing you want to have stored often is a **string** - a line of text.
Strings are indicated with a starting and a leading `"`

(double quote).
You’ll learn about this and other types, as those are called in Python, and
what you can do with them later on.

You can even use a variable to give the turtle a name:

```
timmy = turtle
```

Now every time you type `timmy`

it knows you mean `turtle`

. You can
still continue to use `turtle`

as well:

```
timmy.forward(50)
timmy.left(90)
turtle.forward(50)
```

If we have a variable called `angle`

, how could we use that to experiment
much faster with our tilted squares program?

```
angle = 20
turtle.left(angle)
turtle.forward(50)
turtle.left(90)
turtle.forward(50)
turtle.left(90)
turtle.forward(50)
turtle.left(90)
turtle.forward(50)
turtle.left(90)
turtle.left(angle)
```

... and so on

Can you apply that principle to the size of the squares, too?

Draw a house.

You can calculate the length of the diagonal line with the Pythagorean
theorem. That value is a good candidate to store in a variable. To calculate
the square root of a number in Python, you’ll need to import the *math* module
and use the `math.sqrt()`

function. The square of a number is calculated
with the `**`

operator:

```
import math
c = math.sqrt(a**2 + b**2)
```