Finding a Solution for a System of Equations with Trigonometric Functions

[usn7564]

Homework Statement

It's a longer problem but all that's left is:

$$y = k^2 \frac{1-cos(\theta)}{2}$$
$$x = k^2 \frac{\theta - sin(\theta)}{2}$$

I want to find a k that solves the equations for the point $$(x, y) = (x_0, y_0)$$

The Attempt at a Solution

I manipulated them to get two expressions for k, putting them = each other and simplifying I get

$$2(\theta-sin(\theta)) = 1 - cos(\theta)$$
And now I'm completely stuck, how on Earth do I go about finding what theta is?

 

[SteamKing]

You can always iterate, picking a trial solution value for theta: remember to use radians.

 

[usn7564]

Yeah, that's an option of course. I wonder if that's what the book did, would mean that theta is some relatively nice number I could just find by brute forcing it.
Will give it a go tomorrow, calling it a day for now.