Question

How would you apply the Cosine Angle Difference Identity to find the exact value of cos 75o?

cos (100.5o – 25.5o)
cos (120o – 45o)
cos (180o – 75o)
cos (30o + 45o)

Answer 1

B is the final answer :)

Answer 2

The difference cos(120° - 45°) is most likely the form you would use with that formula.


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The "difference" cos(30° + 45°) could also be used, where 45° is rewritten as -(-45°), or 30° is rewritten as -(-30°).