Prove $\cos \left( x + \frac { \pi } { 4 } \right) + \cos \left( x - \frac { \pi } { 4 } \right) = \sqrt { 2 } \cos x$

question 39

Essay

Prove $\cos \left( x + \frac { \pi } { 4 } \right) + \cos \left( x - \frac { \pi } { 4 } \right) = \sqrt { 2 } \cos x$ .

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Definitions:

Integer Array

A data structure in programming that consists of a collection of integers stored in a contiguous memory location.

Char

A data type in programming used to store a single character within single quotes.

Strcpy

A standard library function in C that copies a string from one location to another.

Message

Information or data conveyed from one process or system to another, often via communication protocols or messaging systems.