If `A+B+C=kpi, k inZ` Then prove that,
`tanA+tanB+tanC=tanA.tanB.tanC`

If tanA+tanB+tanC=tanAtanBtanC then

Prove that, tan3A.tan2A.tanA=tan3A-tan2A-tanA

If A+B+C=kpi, k inZ Then prove that, cotB.cotC+cotC.cotA+cotA.cotB=1 .

Prove that, (tanA+tanB)/(tanA-tanB)=(sin(A+B))/(sin(A-B))

If A + B + C = 180^@ , then prove that sin 2 A+ sin 2B + sin 2C = 4 sin A sin B sin C

By using above basic addition/ subtraction formulae, prove that (i) tan (A+B)=(tan A+tan B)/(1-tan A tan B) , (ii) tan (A-B)=(tan A-tanB)/(1+tan A tan B) (iii) sin2theta=2sintheta costheta , (iv) cos2theta=cos^(2)theta=1-2sin^(2)theta=2cos^(2)theta-1 (v) tan 2theta=(2 tan theta)/(1-tan^(2) theta)

If A and B are acute angles such that tanA=1/2,tanB=1/3 and tan(A+B)=(tanA+tanB)/(1-tanAtanB) , find A+B

Perpendiculars are drawn from the angles A, B and C of an acute-angled triangle onthe opposite sides, and produced to meet the circumscribing circle. If these produced parts are alpha., beta, gamma, respectively, then show that, then show that a/alpha+b/beta+c/gamma=2(tanA+tanB+tanC).

If A+B+C=pi , prove that : cot (A/2)+ cot(B/2) + cot(C/2) = cot(A/2) cot (B/2) cot (C/2)

If the position vectors of the points A,B and C be a,b and 3a-2b respectively, then prove that the points A,B and C are collinear.