CosA+cosB-cosC=4COSA/2 cosB/2 SINC/2-1

if cosA = 4/5; sin <0; cosB = 12/13; 0<B<90, determine sin(A-B) thanks ... :)

prove 1-cosB divided by 1+cosB= tan^2B/2

1-cosA+cosB-cos(A+B)/1+cosA-cosB-cos(A+B)=tan(A/2)ct(A/2)

if sinA+sinB=x and cosA-cosB=y then find tan[(A-B)/2]

Prove that 1-cosA+cosB-cos(A+B)/1+cosA-cosB-cos(A+B) = tanA/2cotA/2

If 1/sinA+1/cosA =1/sinB+1/cosB, prove that: cot(A/2+B/2) = TanA. TanB

Prove that CosB-cosA/cosA+cosB=tanA+B/2tanA-B/2

If sinA+sinB=1/2 and cosA+cosB=1/2 then the value of tanA+tanB

If (cosA)/(cosB)=x/y, then (x tanA+y tanB)/(x+y)=?

If sinA-sinB=x and cosA+cosB=y than tan(A+B/2) is:

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