cos^(2)A+cos^(2)B+cos^(2)C=1-cos A cos B cos C prove that
a(cos C-cos B)=2(b-c)cos^(2)(A)/(2)
A+B=C rArr cos^(2)A+cos^(2)B+cos^(2)C-2cos A cos B cos C=
In a Delta ABC,a(cos^(2)B+cos^(2)C)+cos A(c cos C+b cos B) is equal to
(C) (sin^(2)A+cos^(2)A)/(1-cos^(2)A)
The expression cos^(2)(a+b+c)+cos^(2)(b+c)+cos^(2)a-2cos a*cos(b+c)cos(a+b+c) is indendent of
If 1+^(n)C_(1)cos theta+^(n)C_(2)cos2 theta+.......+^(n)C_(n) equals
b(cos A-a cos C)=c^(2)-a^(2)
If a^(2)+b^(2)+c^(2)=1, then prove that a^(2)+(b^(2)+c^(2))cos phi,ab(1-cos phi),ac(1-cos phi)ba(1-cos phi),b^(2)+(c^(2)+a^(2))cos phi,bc(1-cos phi)ca(1-cos phi),cb(1-cos phi),c^(2)+(a^(2)+b^(2))cos phi is independent of a,b,c.