cos(45)cos(30)

<-- Enter special trig expression or identity

Using the Product to Sum Formula for Trig, Calculate Cos(45°)Cos(30°)

There exists a special identity to simplify this below:
Cos(u)Cos(v) =Cos(u - v) + Cos(u + v)
2

In this case, u = 45 and v = 30
Cos(45)Cos(30) =Cos(45 - 30) + Cos(45 + 30)
2

Cos(45)Cos(30) =Cos(15) + Cos(75)
2

Cos(45)Cos(30) =0.49 + 0.3
2

Cos(45)Cos(30) =8
2

Cos(45)Cos(30) = 0.9