Question

If A,B,C are the interior angles of triangle ABC then show that cosec2(B+C/2) - tan2 A/2=1

Answer 1

Answer:

Sins, 2(A+B+C)=180°

=2(B+C)=180°-2A

=2(B+C/2)=90°-2A/2

=Cosec2(B+C/2)=Cosec2(90°-A/2)

=Cosec 2(B+C/2)=Tan2A/2