Question

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If A+B+C = 180°, then sin(A+B) - sin C=​

Answer 1

Answer:

If the sum of four angles be , prove that the sum of the products of their cosines taken two and two together is equal to the sum of the products of their sines taken similarly.

Answer 2

Answer:

1

We known that A+B+C=180°

=> A+ C=180°-B

=> _A+_C_=180°_-_B_

2 2

=> A_+_C= 90°-B_

2 2

=> tan(A_+C_)=tan (90°-_B_)

2 2

=> tan(_A_+C)=Cot (_B_)

2 2

2

We known that A+B+C=180°

=> B+C=180°-A

=> B_+_C= _180°_-A_

2 2

=> B_+_C=900-_A_

2 2

=> sin(B_+_C)=sin(90°-_A_)

2 2

=> Sin (B_+_C)=cos(_A_)

2 2