In a `Delta ABC, ` show that `(a cos A+b cos B+ c cos C)/(a+b+c)= (r )/(R )`

In a Delta ABC, c cos ^(2)""(A)/(2) + a cos ^(2) ""(C ) /(2)=(3b)/(2), then a,b,c are in

If r and R are radii of the incircle and circum-circle of DeltaABC, then prove that : 8rR{cos ^(2) A//2 +cos ^(2) B//2 +cos ^(2) C//2} =2bc+2ca+2ab-a^(2) -b^(2) -c^(2).

For any triangle ABC, prove that : (cosA)/(a)+(cosB)/(b)+(cosC)/(c)=(a^(2)+b^(2)+c^(2))/(2abc)

In a triangle ABC, sin A- cos B = Cos C , then angle B is

If A , B and C are interior angles of triangle ABC ,then show that sin ((B+C)/( 2) )=cos (A) /(2)

For any triangle ABC, prove that : a(cosC-cosB)=2(b-c)cos^(2)""(A)/(2)

In any Delta ABC, prove the following : r_1=rcot(B/2)cot(C/2)

In a triangle ABC, cos 3A + cos 3B + cos 3C = 1 , then then one angle must be exactly equal to

D is midpoint of BC in Delta ABC such that AD and AC are perpendicular, Show that Cos A Cos C = (2 (c^2-a^2))/(3ac)

For DeltaABC , prove that, (a+b)/(c)=(cos((A-B)/(2)))/(sin""(C)/(2)) .