Solve a quadratic with trigonometric values in degrees

[axekick]

I'm trying to solve for x in the function:

-16.1(15/cos(x))^2 + 800*sin(x)*(15/cos(x)) =2000

It should be a "zeros" problem but my HP50g calculator is making me put it in radians mode and won't solve the equation in degrees. Does anyone know what I'm doing wrong? I can't find an example like this anywhere.