" L "2" ,ufe "A=[[1,1,1],[1,1,1],[1,1,1]]," aो fre thre for "

If A = [[1,1,1],[1,1,1],[1,1,1]], A^(2) =

Find ,A^2-5A+6l, if A = [(2,0,1),(2,1,3),(1,-1,0)] .

Show that the thre angles of the triangle with vertices (1,-1,1), (2,3,-1) and (3,0,2) are, respectively, cos^-1 (2/sqrt(114), cos^-1 4/sqrt(176) and cos^-1 17/sqrt(399))

Show that the thre angles of the triangle with vertices (1,-1,1), (2,3,-1) and (3,0,2) are, respectively, cos^-1 (2/sqrt(114)), cos^-1( 4/sqrt(126)) and cos^-1 (17/sqrt(399))

Suppose (1)/(2)x, lx,+1l,lx-1l,1l are in A.P., then sum to 10 terms of the A.P. is

Two lines with direction cosines l_1,m_1,n_1 and l_2,m_2,n_2 are at righat angles iff (A) l_1l_2+m_1m_2+n_1n_2=0 (B) l_1=l_2,m_1=m_2,n_1=n_2 (C) l_1/l_2=m_1/m_2=n_1/n_2 (D) l_1l_2=m_1m_2=n_1n_2

Two lines with direction cosines l_1,m_1,n_1 and l_2,m_2,n_2 are at righat angles iff (A) l_1l_2+m_1m_2+n_1n_2=0 (B) l_1=l_2,m_1=m_2,n_1=n_2 (C) l_1/l_2=m_1/m_2=n_1/n_2 (D) l_1l_2=m_1m_2=n_1n_2

Show that the matris [[l_(1),m_(1),n_(1)],[l_(2),m_(2),n_(2)],[l_(3),m_(3),n_(3)]] is orthogonal, if l_(1)^(2) + m_(1)^(2) + n_(1)^(2) = Sigmal_(1)^(2) = 1 = Sigma l_(2)^(2) = Sigma_(3) ^(2) and l_(1) l_(2) + m_(1)m_(2) + n_(1) n_(2) = Sigma l_(1)l_(2) =0 = Sigma l_(2)l_(3) = Sigma l_(3) l_(1).