Sum and Difference of Identities

Write the following expression as the sine, cosine, or tangent of an angle.
cos(175)cos(55)+sin(175)sin(55)

• sin(120)

• cos(120)

• cos(230)

• sin(230)

Please choose the correct sum and difference formula:
cos (α-β) =

• sin α cos β + cos α sin β

• sin α cos β - cos α sin β

• cos α cos β - sin α sin β

• cos α cos β + sin α sin β

• A
• B
• C

Use Sum or Difference Identities to find the exact value of each expression.
cos(75°)

• 1/4

• √6/4 - √2 / 4

• √6 + √2 / 4

• -√6/4 - √2 / 4

Find the exact value of the expression.
sin(5π/12)cos(π/4) - cos(5π/12)sin(π/4)

• 1/2

• -1/2

• -√(2)/2

• √(3)/2

• A
• B
• C
• D

• A
• B
• C
• D

• A
• B
• C
• D