In ` Delta A B C` , prove that `t a n A+t a n B+t a n Cgeq3sqrt(3),w h e r eA ,B ,C` are acute angles.

Prove that in Delta ABCtan A+tan B+tan C>=3sqrt(3); where A;B;C are acute angles.

Prove that in ABC,tan A+tan B+tan C>=3sqrt(3) where A,B,C are acute angles.

Prove that in Delta ABCcos A+cos B+cos C<=(3)/(2); where A;B;C are acute angles.

If A+B+C=180^0 , then (t a n A+t a n B+t a n C)/(t a n A t a n B t a n C) is equal to t a n A t a n B t a n C b. 0 c. 1 d. none of these

In triangle A B C ,poin t sD , Ea n dF are taken on the sides B C ,C Aa n dA B , respectigvely, such that (B D)/(D C)=(C E)/(E A)=(A F)/(F B)=ndot Prove that _(D E F)=(n^2-n+1)/((n+1)^2)_(A B C)dot

The medians B E\ a n d\ C F of a triangle A B C intersect at Gdot Prove that area of G B C=a r e a\ of\ q u a d r i l a t e r a l\ AFGE.

prove that | vec axx vec b|=( vec adot vec b)t a ntheta, w h e r e theta is the angle between vec a a n d vec bdot

Statement 1 is True: Statement 2 is True; Statement 2 is a correct explanation for statement 1 Statement 1 is true, Statement 2 is true;2 Statement 2 not a correct explanation for statement 1. Statement 1 is true, statement 2 is false Statement 1 is false, statement 2 is true Statement I: If A is obtuse angle I A B C , then tanB\ t a n C<1 because Statement II: In A B C ,\ t a n A=(t a n B+t a n C)/(t a n B t a n C-1)\ a. A b. \ B c. \ C d. D

In Figure, A B C D is a trapezium in which A B\ D C\ a n d\ D C=40\ c m\ a n d\ A B=60\ c mdot If X\ a n d\ Y are, respectively, the mid-points of A D\ a n d\ B C , prove that: a r\ (t r a pdotD C Y X)=9/(11)\ a r\ (t r a pdot(X Y B A)

In a DeltaABC , prove that Sigma_(r=0)^(n)""^(n)C_(r)a^(r)b^(n-r) cos ( r B-(n-r)A)=c^(n) .