Answer: The correct option is (C) [tex]8\cos^2\theta.[/tex]
Step-by-step explanation: We are given to solve the following trigonometric expression :
[tex]E=(\cos\theta+\cos\theta)^2+(\cos\theta+\cos\theta)^2.[/tex]
The solution of the above expression is as follows :
[tex]E\\\\=(\cos\theta+\cos\theta)^2+(\cos\theta+\cos\theta)^2\\\\=(2\cos\theta)^2+(2\cos\theta)^2\\\\=4\cos^2\theta+4\cos^2\theta\\\\=8\cos^2\theta.[/tex]
Thus, the required solution of the given expression is [tex]8\cos^2\theta.[/tex]
Option (C) is CORRECT.
