In the orthonormal system (O; i⃗,j⃗) below, consider point A(3, −1), vector v⃗(2,1), and straight line (d).
Let (d’) be the line of equation y = −2x + 5.
1. Show that A belongs to (d’).
2. Draw the straight line (d’).
3. Write a Cartesian equation of line (d).
4. What is the relative position of the lines (d)
and (d’)? Justify your answer.
5. Write the reduced equation of the straight
line(D) defined by (A, ⃗v⃗).
6. Deduce that the two lines (D) and (d) are
perpendicular.
7. Determine the coordinates of the point of
intersection I of the two lines (d) and (D).