Angle Identities (Sum/Difference/Double/Half)

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)

sin 105º

• √3/2
• -1/4(√2 + √6)
• 1/4 (√2 + √6)
• 2-√3

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

• A
• B
• C
• D