Marlena has 3 straws. Two straws have the lengths shown. She does not know the length of the shortest straw, but when she forms
2 answers:
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Answer:
See below.
Step-by-step explanation:
First, use the co-function identity:
We can turn the second term into cosine:
Substitute:
Now, use the sum to product formulas. We will use the following:
Substitute:
Use the even-odd identity:
Therefore:
Replace the second term with the original term:
Proof complete.
