If the operation is defined by a b = a2 + b2 for all real numbers a and b, then (2 3) 4 is equal to
120
185
175
129
If and the angle between a and b is , then the area of the triangle formed by these two vectors as two sides is
15
If are the position vectors of the vertices of a ABC taken in order, then A is equal to
D.
Let position vector of the vertices are