Fermi
·
Concept Library
·
Courses
·
Books
·
Problems
·
Simulations
·
Math Wiki
·
High School
Fermi
›
Problems
Mathematics
Mathematics
Problem
Is
cos
(
x
+
y
)
\cos(x+y)
cos
(
x
+
y
)
equal to
cos
x
+
cos
y
\cos x+\cos y
cos
x
+
cos
y
for all real
x
x
x
and
y
y
y
? Give a brief reason for your answer.
Browse the problem library