If `A+B=pi/3a n d\ cos A+cos B=1,\ t h e n-` a.`cos(A-B)=1//3` b. `\ |cos A-cos B|\ =sqrt(2/3)` c.`cos(A-B)=\ -1/3` d. `\ |cos A-cos B|=1/(2sqrt(3))`

If A+B=pi/3a n dcosA+cos B=1, then find the value of cos((A-B)/2dot)

sin(A+B)=1/sqrt(2) cos(A-B)=sqrt3|2

if A+ B + C = pi, and cos A = cos B cos C, show that 2 cot B cot C=1.

If A+B+C =(3pi)/(2) , then cos2A+cos2B+cos2C is equal to-

In triangle ABC, /_C = (2pi)/3 then the value of cos^2 A + cos^2 B - cos A.cos B is equal

If 3t a n At a n B=1, prove that 2cos(A+B)=cos(A-B)dot

Prove that : (sin 2A+sin 2B + sin 2C)/(cos A + cos B + cos C-1) = 8 cos(A/2) cos( B/2) cos( C/2)

If A , Ba n dC are the angels of a triangle, show that |-1+cos B cos C+cos B cos B cos C+cos A-1+cos A cos A-1+cos B-1+cos A-1|=0

If A , Ba n dC are the angels of a triangle, show that |-1+cos B cos C+cos B cos B cos C+cos A-1+cos A cos A-1+cos B-1+cos A-1|=0

In a quadrilateral A B C D , vec A C is the bisector of vec A Ba n d vec A D , angle between vec A Ba n d vec A D is 2pi//3 , 15| vec A C|=3| vec A B|=5| vec A D|dot Then the angle between vec B Aa n d vec C D is cos^(-1)(sqrt(14))/(7sqrt(2)) b. cos^(-1)(sqrt(21))/(7sqrt(3)) c. cos^(-1)2/(sqrt(7)) d. cos^(-1)(2sqrt(7))/(14)