"Show numerically that the composite argument property for cos (A - B) is correct by substituting 37° for A and 21° for B and showing that you get the same answer for both sides of the equation."

My response is:

$\displaystyle cos(37°-21°)=cos(16°)=-0.9576594803

cos(37°-21°)=cos(37°)-cos(21°) does not equal -0.9576594803$

I'm just wondering if I answered the question... the point is that cosine does not distribute.