HTML and CSS Reference
In-Depth Information
-30 degrees
(negative)
30 degrees
(positive)
Figure 3-6.
Angle measurements on the canvas element
You can work out a system to reverse the angles before rendering, or conserve the computation and learn
to live with it. It's suggested you do the latter, and this is the tactic used for all the code in this topic.
Triangle sides
There's not too much to say about the sides of a triangle by themselves, but there are some specific terms
to cover. Until further notice, we are referring to right-angle triangles, where one of the angles is 90
degrees. In this case, the sides have special names, as shown in Figure 3-7. The two sides that touch the
90-degree angle are called
legs,
and the opposite side is called the
hypotenuse.
The hypotenuse is always
the longest side.
Hypotenuse
Leg
Opposite
Angle
90 degrees
Leg
Adjacent
Figure 3-7.
The parts of a right-angle triangle
When referring to the side
opposite
an angle, we're talking about the side that does not touch that angle.
When referring to an
adjacent
side, we mean one of the sides that does touch the angle. Most of the time,
