Math
posted by sophie on .
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?

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. 
it's B?

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 
no those are the options for sure :/

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