solve problem

Question

Write the expression below as a trigonmetric function of a single of a single angle.Then evaluate.

 

 

Write as a trigonmetric function function of a single angle.

 

cos 5^°cos 12^°-sin 5° sin 12^°=

 

 

Evaluate

 

cos 5^°cos 12^°- sin 5^° sin 12^°≈

Answer 1

cos(A+B) = cosAcosB-sinAsinB

 

So, cos5°cos12° - sin5°sin12° = cos(5°+12°)

 

                                                     = cos17° ≈ 0.9563