## kaylala Group Title Find the value of the following using the concepts of both addition and subtraction formulas and reference angle: sin 255 5 months ago 5 months ago

1. kaylala Group Title

@eliassaab

2. kaylala Group Title

@ganeshie8

3. kaylala Group Title

@Callisto

4. eliassaab Group Title

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

5. eliassaab Group Title

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

6. kaylala Group Title

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

7. eliassaab Group Title

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

8. eliassaab Group Title

Did you understand it?

9. kaylala Group Title

no sorry where did you get that?

10. eliassaab Group Title

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.

11. eliassaab Group Title

Have you heard about periodic functions?

12. kaylala Group Title

have no heard of periodic functions ever @eliassaab