Cosine Addition and Subtraction Formulas

Use Sum or Difference Identities to find the exact value of each expression.

cos(75°)

• 1/4

• 
• 
• 

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)

Find the exact value of the expression.
cos(20)cos(40) - sin(20)sin(40)

• 1/4
• 1/2
• √(3)/2
• √(3)