In the equation below, I need to solve for $t$. Can anyone assist with rearranging the equation? My algebra skills have wilted over the years as I spent more time in front of engineering / CAD / GIS applications. Thanks!
$$ s=4r(1-\cos\frac{t}{2}) $$
$$ s = 4r\left(1-\cos \frac{t}{2}\right) $$ $$ \frac{s}{4r} = 1-\cos\frac{t}{2} $$ $$ 1-\frac{s}{4r} = \cos\frac{t}{2} $$ $$ \arccos \left(1-\frac{s}{4r}\right) = \frac{t}{2} $$ $$ 2\arccos \left(1-\frac{s}{4r}\right) = t $$