We need to find a formula for $T(a,b)$ , where T represents the projection on the y-axis along the line $L$ = { (s , s) for s belonging to $R$ } .
I got $T(a,b)$ as $T(a,b)$ = ($0$ , $b-a$) , but how to show this projection graphically ? Please help !
See this picture:
The dashed lines are drawn from the end of the vector toward the two directions, each one parallel to the other direction. So you make a parallelogram with the two directions.