The large red equilateral triangle has sides of 8x units. The midpoints of the red triangle are joined to form the blue triangle. The midpoints of the blue triangle ate joined to form the green triangle. The process of joining midpoints to form new triangles continues indefinitely

Urgent##1. Solve for x if the sum of all the areas is given by 19200 square root 3

2 answers

If you draw it you can see that
An = An-1 * .25
or
a , .25 a , .25^2 a etc

we have a sum of a geometric series here with r = .25
see
http://www.mathsisfun.com/algebra/sequences-sums-geometric.html

the first term a is area of triangle with 8 x sides
a = 2 * 4x * 4x sqrt 3
= 32 sqrt 3

sun of infinite geometric series
= a /(1-r)

= 32 sqrt 3 /.75

= 42.67 sqrt 3
so A total = 32 x^2 sqrt 3/.75
so

32 x^2 sqrt 3/.75 = 19200 sqrt 3

x^2 = 450
x = 21.2

check my arithmetic