Posted by sophie on Monday, June 1, 2009 at 8:26pm.
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  bobpursley, Monday, June 1, 2009 at 8:47pm
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  sophie, Monday, June 1, 2009 at 8:53pm
it's B?

Math  Reiny, Monday, June 1, 2009 at 8:54pm
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  sophie, Monday, June 1, 2009 at 9:11pm
no those are the options for sure :/

Math  MathMate, Monday, June 1, 2009 at 11:22pm
Are you sure it is not
> Use a sum or difference identity to find the exact value of sin255
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