Question

if A, B, C are the interior angles of a ∆ABC,show that:
(1) cos A+B / 2 = sin C/ 2
.

URGENT​

Answer 1

Answer:

$in \: \: triangle \: abc \: \\ a + b + c \: = 180 \\ a + b = 180 - c$

now

cos{180÷2-c/2-90} = sin{90-c/2-90}

cos(90-theta)=sin theta

sin(c/2)=sin(c/2)

LHS=RHS