Answer:
cos(5)cos(40) - sin(5)cos(40) = cos(45) = √(2)/2
Step-by-step explanation:
One of the trig identity (Angle Sum/Difference Identity) is:
cos(α + β) = cos(α) cos(β) – sin(α) sin(β)
We're given: cos(5)cos(40) - sin(5)cos(40)
In this case, α=5 and β=40
Plug it into you're equation
cos(α + β) = cos(α) cos(β) – sin(α) sin(β)
cos(5 + 40) = cos(5)cos(40) - sin(5)cos(40)
cos(5 + 40) = cos(45) = √(2)/2
