Prove that : {{a }, {a, b} } ={{c}, {c. d }}, iff a=c and b=d

Prove that [a xx b,a xx c,d]=(a*d)[a,b,c]

In Figure, A C=B C ,\ /_D C A=/_E C B\ a n d\ /_D B C=E A Cdot Prove that triangle D B C\ a n d\ E A C are congruent, and hence D C=E C\ a n d\ B D=A E

If (a+b)/(b+c) = (c +d)/(d + a) , that prove that c = a " or, " a + b + c + d = 0 .

If A B C D is a parallelogram, then prove that a r\ (\ A B D)=\ a r\ (\ B C D)=\ a r\ (\ A B C)=\ a r\ (\ A C D)=1/2\ a r\ (|""|^(gm)A B C D)

If (a + b + c + d) (a - b - c + d) = (a + b - c - d) (a - b + c - d) , prove that: a : b = c : d .

If a, b, c and d are four coplanr points, then prove that [a b c]=[b c d]+[a b d]+[c a d] .

If a, b, c and d are four coplanr points, then prove that [a b c]=[b c d]+[a b d]+[c a d] .

If a, b, c and d are four coplanr points, then prove that [a b c]=[b c d]+[a b d]+[c a d] .

In Figure, A D=B C\ a n d\ B D=C A . Prove that ∠A D B= ∠B C A a n d ∠D A B=∠ C B A .

In a A B C ,\ \ B D and C E are the altitudes. Prove that A D B and A E C are similar. Is C D B ~ B E C ?