8
QuizMultiple Choice
Trigonometric Double Angle Identities
Question 8 • Precalculus
Which derivation correctly uses the cosine sum identity to prove the cosine double angle identity?
Answer
A
A 2-column table with 3 rows. Column 1 has entries 1, 2, 3. Column 2 is labeled Step with entries cosine (2 x) = cosine (x + x), = cosine (x) cosine (x) minus sine (x) sine (x), = cosine squared (x) minus sine squared (x).
B
A 2-column table with 3 rows. Column 1 has entries 1, 2, 3. Column 2 is labeled Step with entries cosine (2 x) = cosine (x + x), = cosine (x) cosine (x) + sine (x) sine (x), = cosine squared (x) + sine squared (x).
C
A 2-column table with 3 rows. Column 1 has entries 1, 2, 3. Column 2 is labeled Step with entries cosine (2 x) = cosine (x + x), = sine (x) sine (x) + cosine (x) cosine (x), = sine squared (x) + cosine squared (x).
D
A 2-column table with 3 rows. Column 1 has entries 1, 2, 3. Column 2 is labeled Step with entries cosine (2 x) = cosine (x + x), = sine (x) sine (x) minus cosine (x) cosine (x), = sine squared (x) minus cosine squared (x).