Find the value of the following using the concepts of both addition and subtraction formulas and reference angle:

sin 255

Question

Find the value of the following using the concepts of both addition and subtraction formulas and reference angle:

sin 255

kaylala · Answer

@eliassaab

kaylala · Answer

@ganeshie8

kaylala · Answer

@Callisto

anonymous · Answer

$$
\sin (225)=-\sin (360-255)=-\sin (105)=-\sin (45+60)=\-\sin (45)) \cos
   (60)-\sin (60) \cos (45)
$$

anonymous · Answer

$$
-\sin (45)) \cos
   (60)-\sin (60) \cos (45)=-\frac{1+\sqrt{3}}{2 \sqrt{2}}
$$

kaylala · Answer

why is it -sin(360-255)

why the - sign there?

anonymous · Answer

$$
-\sin(360-255)=- \sin (-255) =-(-\sin( 255)) = \sin(255)
$$

anonymous · Answer

Did you understand it?

kaylala · Answer

no
sorry where did you get that?

anonymous · Answer

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.

anonymous · Answer

Have you heard about periodic functions?

kaylala · Answer

have no heard of periodic functions ever @eliassaab