Question

prove sin((a+b)/2) = cos (c/2)

Answer 1

Well for a triangle a+b+c=180
so a+b=180-c

sin((a+b)/2)
here you can substitute a+b with 180-c
sin(180-c))/2
=sin(90-c/2)
=cos c/2

Answer 2

ahhhh... i see i see.. thanks

Answer 3

yw :)

Answer 4

wait... why does the sin180 become sin90? :/

Answer 5

(180-c))/2=180/2-c/2
=90-c/2

Answer 6

gt it?

Answer 7

... yeahhh...