Here’s a little trick I discovered by accident a while back: Go to Google, and put 250-(tan(4pi/6))^2 into the search field. Hey presto! It does the math. This came in handy yesterday as I was evaluating things like
E.x = Origin.x + sqrt(1/((rv2/rh4)(tan2θ) + 1/rv2)
To find the point on an ellipse where the tangent is at a given angle. My little calculator widget was not remotely up to the task.