Question

Prove :-
sin(180-a)=sina
cos(360-a)=cosa
tan(180+a)=tana

Answer 1

use sin(a-b) formula !

Answer 2

\[\large \bf \sin(a-b)=\sin{a}\cos{b}-\sin{b}\cos{a}\]
Put a=180 and b=a

Answer 3

For sine check here:
http://math.stackexchange.com/questions/569105/why-is-sinx-sin180-circ-x

Answer 4

For cos
Since
cos(a-b) = cosacosb + sinasinb
Thus
cos(360 - x) = cos360*cosx + sin360*sinx
with cos360=1 and sin360=0,
thus
cos(360 - x) = cosx

Answer 5

understood jitesh ?

Answer 6

yes i gt it but
how can we gt the general expression for sine i.e;

\[\LARGE{n \pi +(-1)^n \alpha}\]