If `a ,b ,c ,d ,e ,f` are A.M.s between 2 and 12, then find the sum `a+b+c+d+e+fdot`

If a,b,c,d,e, f are A. M's between 2 and 12 , then find a + b + c +d + e +f.

If A={:[(a,2,3),(b,c,4),(d,e,f)]:} is skew symmetric matrix, then find a,b,c,d,e,f.

Let A B C D be a parallelogram of area 124c m^2dot If E and F are the mid-points of sides A B and C D respectively, then find the area of parallelogram A E F Ddot

If D ,\ E ,\ F are the mid points of the side B C ,\ C A and A B respectively of a triangle ABC, write the value of vec A D+ vec B E+ vec C Fdot

In A B C ,/_A=50^0,/_B=70^0 and bisector of /_C\ m e e t s\ A B\ a t\ Ddot find the angles of the triangle A D C and B D Cdot

In a A B C , D and E are points on A B and A C respectively such that D E||B C . If A D=2. 4 c m ,\ \ A E=3. 2 c m ,\ \ D E=2c m and B C=5c m , find B D and C E .

If D ,E and F are three points on the sides B C ,CA and A B , respectively, of a triangle A B C show that the (B D)/(C D)=(C E)/(A E)=(A F)/(B F)=-1

Triangles A B C and D E F are similar. If area ( A B C)=16\ c m^2 , area ( D E F)=25\ c m^2 and B C=2. 3 c m , find E Fdot (ii) If area ( A B C)=9\ c m^2 , area ( D E F)=64\ c m^2 and D E=5. 1 c m , find A Bdot (iii) If A C=19 c m and D F=8c m , find the ratio of the area of two triangles.

In a A B C , D and E are points on the sides A B and A C respectively such that D E// B C If A D=2\ c m , A B=6\ c m and A C=9\ c m , find A E . .

In a A B C , D and E are points on the sides A B and A C respectively such that D E || B C If A D=6\ c m , D B=9\ c m and A E=8\ c m , find A C .