Answer: CD = 3.5
Explanation:
The smaller triangle is an isosceles triangle, with two congruent sides.
Two sides are 4m, and one side is 2m.
If you create a ratio, 4/2, you get that the ratio for that smaller traingle is 2m.
Looking at the bigger triangle, you see that it's sides are part of the smaller triangle, but 3m longer. Add 4m to 3m, and you get that the side is 7m. You see that if do that with both sides, you get that the bigger triangle has two sides that are 7m, so its also an issoselces triangle.
Now we can create a ration where:
4/2 = 7/x
and simplify:
2 = 7/x
isolate x
2x = 7
/2 /2
x = 7/2
x= 3.5m
So side CD = 3.5