If `3tan A tan B=1,` prove that `2cos(A+B)=cos(A-B)dot`

If tan A= cot B, prove that A+ B = 90^(@)

If A,B,C are the angles of a triangle then prove that cosA+cosB-cosC=-1+4cos(A/2)cos(B/2)sin(C/2)

If sin2A= lambda sin 2B prove that (tan(A+B)/tan(A-B))=(lambda+1)/(lambda-1)

If DeltaABC is a right angle triangle then prove that cos^(2)A+cos^(2)B+cos^(2)C=1iffsin^(2)A+sin^(2)B+sin^(2)C=2

For any triangle ABC, prove that : (b+c)cos((B+C)/(2))=acos((B-C)/(2))

If sin A =cos B , then prove that A+B =90 ^(@)

In a A B C , if tan(A/2),tan(B/2),tan(C/2) are in AP, then show that cosA ,cosB ,cosC are in AdotPdot

In a right triangle ABC , right angled at B , if tan A = 1 , then verify that 2 sin A cos A = 1 .

For DeltaABC , prove that, (a+b)/(c)=(cos((A-B)/(2)))/(sin""(C)/(2)) .

If a^2+b^2=23 a b , then prove that log((a+b))/5=1/2(loga+logb)dot