(3)(cos A cos alpha+cos(A+B)cos(B+c))/(cos A sin c+cos(A+B)cos(B+4))=cot c

If A,B,C are the angles of a triangle, show that, (iii) (cos A cos C + cos (A + B) cos(B + C))/(cos A sin C - sin (A + B) cos (B + C)) = cot C .

If A+B+C=180^(@), " then " (cosAcosC+cos(A+B)cos(B+C))/(cosAsinC-sin(A+B)cos(B+C)) simplifies to :

If A+B+C=180^(@), " then " (cosAcosC+cos(A+B)cos(B+C))/(cosAsinC-sin(A+B)cos(B+C)) simplifies to :

(a + b + c) (cos A + cos B + cos C)

(c-b cos A)/(b-c cos A)=(cos B)/(cos C)

If A+ B + C = pi, then cos^(2) A + cos ^(2) B + cos ^(2) C is equal to : A) 1 - cos A cos B cos C B) 1 - 2 cos A cos B cos C C) 2 cos A cos B cos C D) 1 + cos A cos B cos C

a cos A + b cos B + c cos C = 2a sin B sin C