P(4,1) and Q(-3,2) are two given points and R(x,y) is a variable point.
a) Find the area of the trangle PQR in terms of x and y.
b) If R lies on the y-axis and the area of trangle PQR is 12 square units,
find the coordinates of R
Rectangle Coordinates System
2008-05-05 5:44 am
回答 (1)
2008-05-05 7:05 am
✔ 最佳答案
a) Please refer to additional mathematics textbook on co-ordinate geometry and area of triangle.b) Since R is on the y-axis, its co-ordinates will be (0,y).
1) Area of trapezium QR with the x-axis = 3(2+y)/2.
2) Area of trapezium RP with the x-axis = 4(1+y)/2.
3) Area of trapezium QP with the x-axis = 7(1 + 2)/2.
(1) + (2) - (3) = 12, therefore y=5. So R is (0,5).
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