Answer:
tan(x) = -1 ±√5
Step-by-step explanation:
This is a quadratic equation in tan(x). Let z = tan(x). Then the equation is ...
z² = 4 - 2z
z² +2z = 4 . . . . . . . add 2z
z² + 2z + 1 = 5 . . . . add 1 to complete the square
(z +1)² = 5 . . . . . . . . write as a square
z +1 = ±√5 . . . . . . . square root
z = -1 ±√5 = tan(x) . . . . . subtract 1; use definition of z
