Question

cos(75 degrees)cos(15 degrees)

Answer 1

so like the answer is .25

Answer 2

Answer:

  1/4

Step-by-step explanation:

The product to sum identity is useful here:

  cos(α)cos(β) = (1/2)(cos(α+β) +cos(α-β))

  cos(75°)cos(15°) = (1/2)(cos(90°) +cos(60°))

  = (1/2)(0 + 1/2)

  = 1/4

This product of cosines is 1/4.