Make: Robotic Arms

51Chapter 3: Inverse Kinematics for 2D Movement

Sine pertains to the relationship of the side of a

right triangle opposite our desired angle divided

by the hypotenuse of the same right triangle.

Cosine is similar but represents the adjacent side

of the right triangle divided by the hypotenuse

of the triangle. Lastly, tangent is defined as

the relationship of the side of the right triangle

opposite the desired angle divided by the side of

the right angle adjacent to our desired angle. Let’s

ignore the length of our link for now, which would

be our hypotenuse, and look at the tangent. If we

were to write this out as an equation, it would look ...