Question

If A+B+C=90° then prove that `sin^2 (A/2)+sin^2 (B/2) + sin^2 (C/2) = 1-2sinA.sinB.sinC` ?

Answer 1

Fun. Let's check it before we spend too much time on it.

For the easiest numbers, let `A=90^circ, B=C=0^circ.` We get `sin^2 45^circ = 1/2` on the left and `1 - 2 \ sin 90^circ sin 0 sin 0 = 1` on the right. It's false. Cue the deflated trombone, wah wah waaah.

Answer 2

question is incorrect.