Make: Volume 93

OKAY ROBOT Inverse Kinematics Drawbot

2. Calculating 

2

and 

1

Now that we have the values of our c and e

variables, we can solve our innermost angle

variables, β

2

and α

1

. Because these two sub-

angles are a part of the right triangles we’ve been

working with (Figure

L

), we can find their value

easily using the trigonometry function arctan.

3. Calculating 

1

and 

2

Our next step will be to calculate sub-angles β

1

and α

2

. If we look back at our original diagram,

these two are not part of the right triangles

we’ve been working with. They are angles within

the non–right triangle portions of our diagram.

Thankfully, if we recall the law of cosines, ...