Question

Is there a way to write cos(theta) in terms of r only?

Answer 1

\[\cos(\theta) = \frac{R-\delta}{R}\]
where delta is unknown length from top of circle to triangle

Answer 2

Whatever the size of r, whether it is the 1 of the unit circle or otherwise, theta remains the same in your scenario.

In other words, theta does not depend on r and is not therefore a function of r.

Turning it around, whatever theta is does not affect the radius.

Answer 3

ok makes sense thanx

Answer 4

ur welcome.