[" 9.किसी "/_ABC" में सिद्ध कीजिए कि "],[qquad c^(2)=b^(2)+a^(2)-2ab cos C]

सिद्ध कीजिए कि |vecA xx vecB|^(2) + |vecA * vecB|^(2) = (AB)^(2).

सिद्ध कीजिए कि 2tan^(-1)sqrt((b)/(a))=cos^(-1)((a-b)/(a+b))

Prove by vector method that in a Delta ABC, c^(2) = a^(2) + b^(2) - 2ab cos C .

In Delta ABC prove that a^(2)+b^(2)+c^(2)=2(bc cos A+ca cos B+ab cos C)

In Delta ABC, prove that a^(2)+b^(2)+c^(2)=2(bc cos A+ca cos B+ab cos C)

In any Delta ABC, prove that :a^(2)+b^(2)+c^(2)=2(bc cos A+ca cos B+ab cos C)

In any triangle ABC, then by vectors, prove that : c^2=a^2+b^2-2ab cos C .

Prove in any triangle ABC that (i) a^(2)+b^(2)+c^(2)=2(bc cos A +ca cos B+ ab cos C) (ii) (b+c) cos A+(c+a)cos B+(a+b) cos C = a+b+c .

Prove that in any triangle ABC(i) c^(2)=a^(2)+b^(2)-2ab cos C( ii) c=b cos A+a cos B