A tetrahedron has vertices O (0,0,0), A(1,2,1,), B(2,1,3) and C(-1,1,2), the angle between faces OAB and ABC will be

A tetrahedron has vertices O(0,0,0),A(1,2,1),B(2,1,3),a n dC(-1,1,2), then angle between face O A Ba n dA B C will be a. cos^(-1)((17)/(31)) b. 30^0 c. 90^0 d. cos^(-1)((19)/(35))

Prove that the tetrahedron with vertices at the points O(0,0,0),\ A(0,1,1), B(1,0,1)a n d\ C(1,1,0) is a regular one.

Find the angles of /_\ABC whose vertices are A((-1,3,2), B(2,3,5) and C(3,5,-2) .

Show that (-1/2,2,0) is the circumacentre of the triangle whose vertices are A (1, 1, 0),B(1, 2, 1) and C (-2, 2, -1) and hence find its orthocentre.

If the volume of tetrahedron A B C D is 1 cubic units, where A(0,1,2),B(-1,2,1) and C(1,2,1), then the locus of point D is a. x+y-z=3 b. y+z=6 c. y+z=0 d. y+z=-3

If A,B,C are points (1,0,-1), (0,1,-1) and (-1,0,1) respectively find the sine of the angle between the lines AB and AC.

Find the orthocentre of Delta A B C with vertices A(1,0),B(-2,1), and C(5,2)

Find the orthocentre of Delta A B C with vertices A(1,0),B(-2,1), and C(5,2)

Prove that the points O(0,0,0), A(2.0,0), B(1,sqrt3,0) and C(1,1/sqrt3,(2sqrt2)/sqrt3) are the vertices of a regular tetrahedron.,

Find the angles of a triangle whose vertices are A(0,-1,-2),B(3,1,4) and C (5,7,1).