If cosa+cosb=2 then cos (a+b) is?

If sinA+sinB=a and cosA+cosB=b,then cos(A+B)

If cosA+cosB+cosC=0, then cos3A+cos3B+cos3C is equal to

If sinA+sinB=a and cosA+cosB=b then prove that sin(A+B)=(2ab)/(a^2+b^2) and cos(A+B)=(b^2-a^2)/(a^2+b^2)

If a cosA=b cosB, then triangleABC is

If A+B+C=pi , prove that : sinA cosB cosC +sinB cosC cosA + sinC cosA cosB = sinA sinB sinC .

If cosA=4/5 and cosB=12/13 , then find the values of cos(A+B) and sin(A-B) , where A , B ((3pi)/(2) to 2pi ) .

If A+B=pi/3 , and cosA+cosB=1 , then which of the following is true:

In A B C , if A B=c is fixed, and cosA+cosB+2cos C=2 then the locus of vertex C is ellipse (b) hyperbola (c) circle (d) parabola

In a triangle ABC, Prove that: sin^3A+sin^3B+sin^3C = 3cosA/2 cosB/2 cosC/2 +cos (3A)/2 cos (3B)/2 cos (3C)/2

Let cosA+cosB=x,cos2A+cos2B=y,cos3A+cos3B=z ,then which of the following is true