The answer : 4 sin c sin b sin a
Step by step
Formula = A+b+c = 180
B+c = 180-A
C+A= 180-B
A+B= 180-c
2 sin c • 2 cos a-b+c/ 2 cos a-b-c / 2
4 sin c cos 180-2b/2 cos a-(180-a)/ 2
4 sin c cos (90-b ) cos ( A-90)
4 sin c sin b sin A
Step by step
Formula = A+b+c = 180
B+c = 180-A
C+A= 180-B
A+B= 180-c
2 sin c • 2 cos a-b+c/ 2 cos a-b-c / 2
4 sin c cos 180-2b/2 cos a-(180-a)/ 2
4 sin c cos (90-b ) cos ( A-90)
4 sin c sin b sin A