# I Involute Equation

1. Jul 23, 2016

Does this involute equation is correct?

2. Jul 23, 2016

### QuantumQuest

It is the parametric equation of the involute of a circle in Cartesian coordinates.

3. Jul 24, 2016

Um, I don't know . What do you think it is?

4. Jul 24, 2016

### QuantumQuest

5. Jul 24, 2016

### rcgldr

Wiki article:

http://en.wikipedia.org/wiki/Involute#Involute_of_a_circle

This is also the path of an object connected to a string that wraps or unwraps around a circular post. The string would be the black line in the wiki animation. The string is always perpendicular to the instantaneous path of the object, and always tangent to the circular post.

6. Jul 25, 2016

So, does this involute equation is correct?

7. Aug 1, 2016

Why no one can answer my question?

8. Aug 1, 2016

### micromass

Staff Emeritus

9. Aug 1, 2016

Is the " t " in degree or radian?

10. Aug 1, 2016

### micromass

Staff Emeritus

11. Aug 1, 2016

OK, now let me work for the equation.

x = r(cos t + t sin t)
y = r(sin t - t cos t)

x = 1(cos 0 + 0 sin 0)
= 1(cos 0)
=1(1)
= 1

y = 1(sin 0 - 0 cos 0)
= 1(sin 0)
= 0

Is it correct?

12. Aug 1, 2016

### micromass

Staff Emeritus
Yes.