Answer:
The required trigonometric form is 
Step-by-step explanation:
Given : Complex number 
To find : Express the complex number in trigonometric form?
Solution :
The complex number
trigonometric form is
Where, 
and 
On comparing with given complex number 
a=-2 and 
Substitute the value,










Substituting all values in the formula,



Therefore, The required trigonometric form is 