1. If a and b denote the vectors OA and OB, indicate on the same diagram the vectors OC and OD denoted by a + b and a a b. Draw on another diagram the vector OE denoted by a + 2b

Question

Vector algebra

Comments

Please clarify the meaning of vector OD. (a a b?)

Answer 1

I'm assuming that OD=a-b (the text says a a b, which appears to me to be meaningless).

The vectors OA (a) (red) and OB (b) (blue) are shown. Vectors OC (c)=a+b (purple) and OD (d)=a-b (tan) are also shown with additional vectors in broken coloured lines to show how the other vectors are created geometrically. The vector AC is b extended from point A, while vector OG is -b. Vector DG is an extended from point G. Vector AX is a extended from point A to be added to vector XE, which is b extended from point X to form vector e=2a+b (green).