In studying the emission of light, in order to determine the angle at which the intensity is a given value, the equation sin^2 A − 4sin A+1= 0 must be solved.
Find the angle A to 0.01°. (sin2 A = (sin A)^2)
sinA= (4+-sqrt(16-4))/2
Sin A= 2+-sqrt(3)
A= arcsin (2+-1.732)
Notice you can only use the - answer in your understanding of the sin funcion. Hyperbolic functions you will get in college, hopefully, that will allow you to do the + root.