SOLUTION: How do you find the cos of 55 degrees using the sum and difference identity?
cos (x + y) = (cos x) (cos y) - (sin x) (sin y) and
cos (x - y) = (cos x) (cos y) +
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-> SOLUTION: How do you find the cos of 55 degrees using the sum and difference identity?
cos (x + y) = (cos x) (cos y) - (sin x) (sin y) and
cos (x - y) = (cos x) (cos y) +
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Question 261459: How do you find the cos of 55 degrees using the sum and difference identity?
cos (x + y) = (cos x) (cos y) - (sin x) (sin y) and
cos (x - y) = (cos x) (cos y) + (sin x) (sin y)
I can't find 2 angles that add or subtract to get 55.
Ex: 315 - 270 = 45 degrees, not 55
There aren't any special angles that will give 55°.
I suspect that the problem was a book typo, and
should have been 75°, perhaps, which could have
geen gotten with 45°+30°
Edwin
