Question 5
Find the ratio in which the line segment joining and is divided by the -axis. Also find the coordinates of the point of division.
- Any point on the -axis has coordinates of the form , meaning its -coordinate is always .
- By the section formula, the coordinates of a point dividing the segment joining and in the ratio are:
- Setting the -coordinate equal to gives the value of , which gives the ratio. Substituting back into the formula gives the -coordinate of the point of division.
Step 1 · Find the Ratio
Let the point of division on the -axis be , and let it divide the line segment joining and in the ratio .Using the section formula for the -coordinate:
Therefore, the -axis divides the line segment in the ratio (i.e., is the midpoint of ).
Step 2 · Find the Coordinates of the Point of Division
Substitute into the section formula for the -coordinate:
Thus, the coordinates of the point of division are .
Ratio is and the coordinates of the point of division are
- Axis Coordinate Confusion: Assuming instead of for a point on the -axis. Remember that on the -axis, , while on the -axis, .
- Coordinate Order: Swapping with when multiplying by and . For ratio from to , multiplies the coordinates of and multiplies the coordinates of .
More questions in Exercise 7.2
Find the coordinates of the point which divides the join of and in the ratio .
Find the coordinates of the points of trisection of the line segment joining and .
To conduct Sports Day activities, in your rectangular shaped school ground , lines have been drawn with chalk powder at a distance of each. flower pots have been placed at a distance of from each other along , as shown in Fig. 7.12. Niharika runs the distance on the 2nd line and posts a green flag. Preet runs the distance on the eighth line and posts a red flag. What is the distance between both the flags? If Rashmi has to post a blue flag exactly halfway between the line segment joining the two flags, where should she post her flag?
Find the ratio in which the line segment joining the points and is divided by .
Find the ratio in which the line segment joining and is divided by the -axis. Also find the coordinates of the point of division.
If , , and are the vertices of a parallelogram taken in order, find and .
Find the coordinates of a point , where is the diameter of a circle whose centre is and is .
If A and B are and , respectively, find the coordinates of P such that and P lies on the line segment AB.
Find the coordinates of the points which divide the line segment joining and into four equal parts.
Find the area of a rhombus if its vertices are , , and taken in order.
[Hint : Area of a rhombus = (product of its diagonals)]