Sum and Difference Trig

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

• 1/4

• ( √(6) - √(2) ) / 4

• (√(6) + √(2)) / 4

• (-√(6) - √(2)) / 4

Assume A and B are positive acute angles. If sinA=15/17 and cosB=4/5, find the cos(A - B).

• 3/8

• 8/17

• -13/85

• 77/85

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)

How could you break up sin(π/12°) to use the sum or difference formulas and the unit circle?

• sin(π-11π/12)

• sin(π)-sin(11π/12)

• sin(π/3-π/4)

• sin(π/3)-sin(π/4)

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

How can the sine of the sum of two angles be calculated?

• sin(α+β) = sinαcosβ + cosαsinβ

• sin(α+β) = sinαsinβ + cosαcosβ

• sin(α+β) = cosαcosβ - sinαsinβ

• sin(α+β) = cosαsinβ - sinαcosβ

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

Given tan α = 3/4 and tan β = (-1/2) Please find the sum and difference: tan (α-β)=

• 2

What is the sum formula for cosine?

• cos(α+β) = sinαsinβ - cosαcosβ

• cos(α+β) = cosαsinβ + sinαcosβ

• cos(α+β) = sinαcosβ + cosαsinβ

• cos(α+β) = cosαcosβ - sinαsinβ