1.

ABC are interior angle of triangle ABC prove that sin (B+C) ➗ 2=cosA/2

Answer» HEY!

in a triangle ABC;

A+B+C = 180°

=) B+C = 180°-A

Divide both sides by 2;

=) (B+C) /2 = 180°/2 - A/2

=) (B+C) /2 = 90°- A/2

take sin in both sides;

=) sin(B+C) /2 = sin {90° - (A/2)}

=) sin(B+C) /2 = COS A/2

hope it helps you!!


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