Question

Which expression is equivalent to cos(40°)cos(10°) + sin(40°)sin(10°)?

sin(40° – 10°)
cos(40° + 10°)
sin(40° + 10°)
cos(40° – 10°)

Answer 1

Answer:

Cos ( 40 + 10)

Step-by-step explanation:

The expression Cos( A + B)

Can be written as;

CosA CosB - SinASin B

Applying this particular case in this question;

Cos (40 + 10) = cos 40cos 10 - sin 40 sin 10

Answer 2

Answer:

its cos(40-10)

Step-by-step explanation: