Thursday 22 February 2018

Coordinate geometry

Coordinate geometry involves calculating the midpoint, slope, distance, and the equation of a line or line segment; you may also be required to find the intersection between two lines.

Sample question

(a) Write down the coordinates of point A and point B on the diagram.

(b) Mark in the point D (6, 8) on the diagram.

(c) Find the co-ordinates of C, the midpoint of [AB].

(d) Join A to D. Join B to D. Join C to D.

(e) Use the distance formula to find |AD| and |BD| .

(f) What type of triangle is ABD? Give a reason for your answer.

Answer: Isosceles

Reason: The lengths of two sides are equal, | AD | = | BD |

(g) State whether the triangles ACD and BCD are congruent. Give a reason for your answer.

Answer:Yes, they are congruent

Reason: | AC | = | BC | as C is the midpoint of [AB]

| AD | = | BD | from part (e)

| CD | = | CD | common side

SSS - congruent triangles

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