in a triangle ABC the value of sin2A+sin2B+sin2C=? where a,b ,c are lengths of sides of triangle

sin A÷a=sin B÷b=sin C÷c=ksin A=ka sin B=kb sin C=kcsin ^2 A=k^2×a^2 sin ^2 B=k^2×b^2 sin ^2 C=k ^2×c^2sin ^2 A+sin ^2 B+sin ^2 C=k^2 (a^2+b^2 +c^2