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Math

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Use a sum or difference identity to find the exact value of sin225°
a. (-√2 - √6)/4
b. (√6 - √2)/4
c. (√6 + √2)/4
d. (√2 - √6)/4

is it A?

  • Math -

    a) is the sine of 285
    b) is the sine of 15, 165
    c) is the sine of 75, 105
    d) is the sine of -15, 195

    check my thinking.

  • Math -

    it's B?

  • Math -

    none of the given answers is correct.
    Are you sure you typed it correctly?

    sin 225 = sin(180+45)
    = sin180cos45 + cos180sin45
    = 0 + (-1)√2/2
    = -√2/2

  • Math -

    no those are the options for sure :/

  • Math -

    Are you sure it is not
    > Use a sum or difference identity to find the exact value of sin255

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