The cross product of the vectors will be orthogonal to both: axb [tex]=<1,3,1>x<1,12,1> = i j k 1 3 1 1 12 1 =<3-12, -1+1, 12-3> =<-9,0,9> Since it is required to have positive first coordinate, we reverse the sign of the components, namely reverse the direction of the vector, which is still orthogonal to both a and b: Required vector is <9,0,-9> which is orthogonal to both a and b.
Count the units on the sides. On the Y axis the rectangle is 4 units and on the X axis the rectangle is 6 units. Area of a rectangle=L*W so, 6*4=24. Perimeter is 4*2 and 6*2=8+12=20. Hope this helps!
