A point taken on each median of a triangle dividesthe median in the ra...
Let A (0,0); B (4m , 0) and C(4p , 4q)
M1 (2m + 2p, 2q)
M2 (2p , 2q) and M3 (2m , 0)
Let E , F and G be the point on the median.
E = (2m + 2p) / 4, 2q / 4) = ((m + p) / 2, q / 2)
F = ((2p + 12m) / 4, (2q + 0) / 4) = ((p + 6m) / 2, q / 2)
G = ((2m + 12p) / 4, (0 + 12 q) / 4) = ((m + 6p ) / 2, 3q)
Area of traingle ABC = 1/2
Area of traingle ABC = 1/2 {(0,0,0) (4m,0,1) (4p,4q,1)}
=1/2(16) = 8 unit
Area of triangle EFG = 1/2 {((m + p) / 2, q / 2, 1)) ((p + 6m) / 2, q / 2, 1) ((m + 6p)/2, 3q, 1)}
= 25/8 unit
ar (EFG) /ar (ABC) = {25 / 8} / 8
= 25/64
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A point taken on each median of a triangle dividesthe median in the ra...
Solution:
Let ABC be the triangle with medians AD, BE, and CF, and let P, Q, and R be the points where the medians are divided in the ratio 1:3, as shown in the figure.
[Note: In what follows, we will use the fact that the medians of a triangle divide each other in the ratio 2:1. This can be proved by using the law of cosines to show that the square of the length of a median is equal to the sum of the squares of half the lengths of the other two sides of the triangle.]
1. Finding the coordinates of the points P, Q, and R:
Let A = (0,0), B = (b,0), and C = (c,d) be the vertices of the triangle, where b and c are positive numbers and d is a positive or negative number. Then the equations of the medians are:
AD: x = b/2
BE: y = d/3
CF: y = (d/2) - (c/4)
Let P = (p,q) be the point on AD such that AP/PD = 1/3. Then we have:
p = (2/3)(b/2) = b/3
q = (1/3)(0) + (2/3)(d/2) = d/3
Similarly, we can find the coordinates of Q and R:
Q = ((2/3)b, (1/3)d)
R = ((1/3)c, (2/3)(d/2)) = ((1/3)c, d/3)
2. Finding the area of the triangle with vertices P, Q, and R:
Let T be the triangle with vertices P, Q, and R. Then the side lengths of T are:
|PQ| = (1/3)b
|QR| = (1/3)sqrt(13)(d/2)
|RP| = (1/3)sqrt(13)(c/2)
To find the area of T, we can use Heron's formula:
s = (1/2)(|PQ| + |QR| + |RP|) = (1/3)(b/2 + sqrt(13)(d/4) + sqrt(13)(c/4))
A = sqrt(s(s-|PQ|)(s-|QR|)(s-|RP|))
After simplifying, we get:
A = (sqrt(3)/36)(b*sqrt(13)d - c*sqrt(13)d + 2bc)
3. Finding the ratio of the areas of T and ABC:
To find the ratio of the areas of T and ABC, we just need to divide the area of T by the area of ABC. Let M be the midpoint of BC, and let h be the altitude of ABC from A. Then we have:
Area of ABC = (1/2)bh
Area of T/ Area of ABC = (A/T)/(bh)
After substituting the expressions for A and T, we get:
Area of T/ Area of ABC = (sqrt(3)/36)(b*sqrt(13)d - c*sqrt(13)d + 2bc)/(bh)
Using the fact that AM = (2/3)h, we can eliminate d from the