Question

TT
11.
Suppose that A+B+C =
i)
cos(B+C)
Σ
cos Bcos C
Then prove the following:
2
= 2 if A, B, C are positive.
Σ
sin(B-C)
= 0 (if none of sina, sinB, sinC is zero)
sin B sin C​

Answer 1

Answer:

TT

11.

Suppose that A+B+C =

i)

cos(B+C)

Σ

cos Bcos C

Then prove the following:

2

= 2 if A, B, C are positive.

Σ

sin(B-C)

= 0 (if none of sina, sinB, sinC is zero)

sin B sin C