Question

in a triangle,prove that sin(c/2)=cos((a+b)/2) (doesnt matter what triangle)

Answer 1

a+b+c=180, so
c = 180 - (a+b)
this is a start

Answer 2

allrdy there :p

Answer 3

c = 180 - (a+b)
divided by 2 on both sides, get
c/2 = 90 - (a+b)/2

Answer 4

plug sin on both sides, get
sin(c/2) = sin(90 - (a+b)/2)

Answer 5

finally, use the identity :
sin(90 - x) = cosx, to simplify the right side above. get

sin(c/2) = sin(90 - (a+b)/2)
sin(c/2) = cos((a+b)/2)

Answer 6

does that make sense ?

Answer 7

ye really thx dude :p

Answer 8

alhamdulillah, you're welcome bro :)