If `A+B+C=pi/2` then `sumcos(B+C)/(cosBcosC)=`

If A+B+C=(pi)/2, " then " sum (cos (B+C))/(cos B cos C)=

If A+B+C=(pi)/(2) then cos(A+C)=

If A+B+C=pi then sin(A+B)+cos(A+C)=

If A+B+C=pi , then cos B+cos C=

If A+B+C=pi then cos((B)/(2))+cos((C)/(2)) equals

if A + B +C= pi/2 ,prove that cos(A - B - C)+ cos (B-C- A) + cos (C- A - B)= 4 cos A cos B cos C

If A+B+C=pi then prove that cos((A)/(2))+cos((B)/(2))+cos((C)/(2))=4cos((pi-A)/(4))cos((pi-B)/(4))cos((pi-C)/(4))

If A + B + C = pi " and " cos A = cos B cos C, "show that" 2 cot B cot C = 1