Question

If A,B and C are interior angles of tringle ABC then show that sec A+B/2 = cosec B/2

Answer 1

In ABC

a+b+c=180

a+b=180-c

(a+b)/2=90-c/2

sec{(a+b)/2}=sec{90-c/2}

sec(a+b)/2=cosec c/2