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kaylala
Find the value of the following using the concepts of both addition and subtraction formulas and reference angle: sin 255
\[ \sin (225)=-\sin (360-255)=-\sin (105)=-\sin (45+60)=\\-\sin (45)) \cos (60)-\sin (60) \cos (45) \]
\[ -\sin (45)) \cos (60)-\sin (60) \cos (45)=-\frac{1+\sqrt{3}}{2 \sqrt{2}} \]
why is it -sin(360-255) why the - sign there?
\[ -\sin(360-255)=- \sin (-255) =-(-\sin( 255)) = \sin(255) \]
Did you understand it?
no sorry where did you get that?
If you add 360 to an angle you do not change the sine of that angle sin(360+y) = sin(y) sin( 360 +(-x)) =sin(-x) = -sin(x) If you do not know these elementary facts, please review them in your book or notes.
Have you heard about periodic functions?
have no heard of periodic functions ever @eliassaab