Precalculus 5.4 Sum and Difference Formulas

This lesson explains the sum and difference formulas in trigonometry. In alignment with Larson's 7th edition Precalculus, it has plenty of examples and worked-out practice problems. #Shaffer, #Precalculus, #Larson, #trigonometry, #sumdifferenceformula, #examples, #problems, #tutor, #tutorial, #free, #homeschool