Question

If A,B,C are the interior angles of a triangle ABC, show that sin ( + 2 ) 2 + ( + 2 ) 2 = 1

Answer 1

Answer:

Step-by-step explanation:

 Sin[(B+C)/2]

Since A+B+C=180 for interior angles of triangle ABC.

then B+C=180-A.

NOW   Sin [(180-A)/2]

             =Sin[90-(A/2)]                      since Sin(90-A)=CosA

              =Cos(A/2)

Answer 2

Answer:

Step-by-step explanation: Sin[(B+C)/2]

Since A+B+C=180 for interior angles of triangle ABC.

then B+C=180-A.

NOW   Sin [(180-A)/2]

             =Sin[90-(A/2)]                      since Sin(90-A)=CosA

              =Cos(A/2)