How can I solve this transcendental equation graphically?

n1=1.77, n2=1.45, n3=1, V=6.378, aE=1.07. Xi is the variable. I want to solve this equation graphically so that solutions will be the points at the interaction of two lines. Any information would be appreciated.

Answer 1

[Mischa Kim]

Timaway, define a vector Xi, e.g. using the linspace command. Then plot tan(Xi) and the right side of your equation into the same figure and find the intersection point.