# 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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