I can't figure out how to get the limit in this problem. I know that 1−cosxx=0 but I'm not allowed to use L'Hopital's Rule. I also already know that the answer is −2536 but I don't know the steps in between. I've already tried multiplying by the conjugates of both the numerator and the denominator but neither are getting me anywhere close. Here is the question:
limx→01−cos5xcos6x−1
Answer
Outline: Our expression is equal to
−1+cos6x1+cos5x⋅1−cos25x1−cos26x,
which is
−1+cos6x1+cos5x⋅sin25xsin26x.
To find
limx→0sin5xsin6x,
rewrite as
56limx→0sin5x5xsin6x6x.
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