" If "AD,BE,CF" are internal bisectors of the angles of "/_ABC," then "(cos(A)/(2))/(AD)+(cos(B)/(2))/(BE)+(cos(C)/(2))/(CF)=

If AD, BE , CF are internal bisectors of the angles of Delta ABC, " then " (cos A//2)/(AD) + (cos B//2)/(BE) + (cos C//2)/(CF) =

If f,g,h are internal bisectoirs of the angles of a triangle ABC, show that 1/f cos, A/2+ 1/g cos, B/2+1/h cos, C/2= 1/a+1/b+1/c

If A,B,C are the angles of a triangle ABC that cos((3A+2B+C)/(2))+cos((A-C)/(2))=

If A, B, C are interior angles of triangle ABC, prove that :- cos^2(A/2)+cos^2((B+C)/2)=1 .

AD, BE, CF are internal angular bisectors of Delta ABC and I is the incentre. If a(b+c)sec.(A)/(2)ID+b(a+c)sec.(B)/(2)IE+c(a+b)sec.(C )/(2)IF=kabc , then the value of k is (a) 1 (b) 2 (c) 3 (d) 4

AD, BE, CF are internal angular bisectors of Delta ABC and I is the incentre. If a(b+c)sec.(4)/(2)ID+b(a+c)sec.(B)/(2)IE+c(a+b)sec.(C )/(2)IF=kabc , then the value of k is