Answer:
AC=18
Explanation:
Let's look at the smaller triangle first. Side AB is 2.5, side BC is 3.5 and side AC is 4.5. Now, looking at the larger triangle, we see that side AB is 10, side BC is 14 and side AC is unknown.
So, how do we find side AC?
First, let's take a look at the other sides available to us—how about AB? On the smaller triangle, AB=2.5, and on the larger triangle AB=10. So, what's their relation?
Well, let's first divide the two by each other: 10/2.5, of which gets us 4. Now, this in itself gives us answer, but let's just double check to be sure. So, taking side BC on the smaller triangle, 3.5, and on the larger triangle, 14, we then divide the two again. 14/3.5 and- look at that! We get 4 again again.
This tells us that 4 is then our multiplier, so we can write the equation as follows: 4.5 (of which we get from the smaller triangle) *4=?. So, with the equation 4.5*4, we get 18 as our answer for ?, or simply the unknown side "a".