Step-by-step explanation:
We can prove the statement is false by proof of contradiction:
We know that cos0° = 1 and cos90° = 0.
Let A = 0° and B = 90°.
Left-Hand Side:
cos(A + B) = cos(0° + 90°) = cos90° = 0.
Right-Hand Side:
cos(A) + cos(B) = cos(0°) + cos(90°)
= 1 + 0 = 1.
Since LHS =/= RHS, by proof of contradiction,
the statement is false.
