∠kl is an angle, and ∠klm is a interior angle. Both are important in the construction of roofs.

Angle roofing systems are very popular due to how easy they are to use. They can be shaped like a box, or an elongated rectangle. The *length gives flexibility* in how the roof is configured.

An adjacent interior angle is one that is adjacent to another angle on the same plane as the first angle. This *second angle must* be parallel to the first, and must be acute (have a sharp right or left turn).

This article will talk about which angles are an interior angle, and how to tell if it is an adjacent internal or externalangle.

## Determine which one is closest to 90 degrees

When two objects are next to each other in space, angle is determined by which one is taller or wider. For example, a sharp angle is narrower than a flat surface, and a thick line is thinner than a thin line.

Angles are measured in degrees, so it is easy to calculate which one is the *closest 90 degree angle*. The smallest angle that can be measured on a painting or print is **15 degrees**, so most angles are 15-degree angles.

If you want to create an adjacent 30- or 45-degree angle, you *must take away 15 degrees* from the corresponding 90-degree angle. This must be done on all your paintings and prints, as the thickness of the *lines varies based* on size.

## Calculate the measure of the largest angle

When the angle is small, such as when you angle yourself into a bed or sofa, it can be calculated using the measure of the smaller angles.

When the angle is large, such as when you turn in a bed or roll in a sofa, it must be measured using all four directions. This is because if you only had three sides to it, **one side would** be bigger than the other two.

So if your room had a **north facing window** and a *south facing window*, then *one would* have an east and west orientation to your room. This is why these two angles are required to be measured.

If you needed more information on this topic, please ask your questions at www.thinkingtocreate.

## The adjacent interior angle is equal to the largest angle minus 90 degrees

This is known as the adjacent angle. When creating an angle, the adjacent angle is equal to the **smallest angle minus 15 degrees**.

For example, a 15-degree angle is adjacent to a 45-degree angle, so the 45-degree angle is null and the 15-degree angle is positive.

Using the same example, if the smallest angles were 10 degrees and 5 degrees, then there would be no null and *positive angles would* be possible. There are **also possible angles** when only one value for each length of angle exists. These are *called distinct angles*.

These are noted in metric measurements as s or l depending on whether they are short or long.

## Repeat for all five angles

Next, determine whether the angle is an adjacent or non-** adjacent interior angle**.

If it is an adjacent angle, the *two angles together form* an internal triangle with the third being a vertical line and the final angle being a horizontal line.

An adjacent angle has more space inside it than an adjacent interior or non-adjacent interior angle. Because of this, there is more room for a ∠ mark on the chart.

If it is not an adjacent angle, then there are no conditions to check. ∠km, ∠lk, and ∠mk do not exist! There are *still five angles* on each side, so repeat for all five sides to determine if they are an exterior, interior, or non-interior angle.