# In `Delta` ABC Prove that : sin (A/2) + sin (B/2) + sin (C/2) = 1 + 4cos[(`Pi`-A)/4]cos[(`Pi`-B)/4]cos[(`Pi `-C)/4]

gsenviro | Certified Educator

please check your question again. There seems to be some error with your equation. You can check by using any set of values of A, B and C. I tried with (60,60,60) and (90,45,45).

Use the fact that A+B+C = pi

and hence pi-A = B+C, etc.

kspcr111 | Student

Please check the full solution of ur question in the attachments .......

In a triangle the sum of the angles is 180 so A+B+C=180

Images:
This image has been Flagged as inappropriate Click to unflag
Image (1 of 2)
This image has been Flagged as inappropriate Click to unflag
Image (2 of 2)
ord99 | Student

It should be

Prove that : sin (A/2) + sin (B/2) + sin (C/2) = 1 + 4sin[(`Pi` -A)/4]sin[(`Pi` -B)/4]sin[(`Pi` -C)/4]

ord99 | Student

There is an error in the question

It should have been

In ABC

Prove that : sin (A/2) + sin (B/2) + sin (C/2) = 1 + 4sin[(-A)/4]sin[(-B)/4]sin[(-C)/4]