2.4 Sum and Difference Formulas - Problem Check-in

cos (A - B)= (leave no spaces in answer)

• A
• B
• C
• D

Fill in the rest after the plus sign (no spaces):

sin(A+B)=sinAcosB +

If  $\sin\alpha=\frac{5}{13}$  and  $\cos\beta=\frac{4}{5}$  (both in QI), then find  $\sin\left(\alpha-\beta\right)$  

•  $\frac{16}{65}$  

•  $-\frac{16}{65}$  

•  $\frac{65}{16}$  

•  $-\frac{65}{16}$  

sin (A - B) = (leave no spaces when typing answer)

Find the exact value.
cos (5π/18 - π/9)

• √(3)/2
• 1/4
• 1/2
• 1

cos (A + B)= (leave no spaces in answer)

Use a sum or difference formula to find an exact value of sin 105º