Question

Using the following diagram, solve for x.

Answer 1

The answer to this equation is x=63

Answer 2

`x=10.5`

Explanation:

Use Thales' Theorem which says: If two lines, not necessarily parallel, are cut by a system of parallel lines, then the segments that result on one of the two lines are proportional to the corresponding segments obtained on the other.

Take a look at the picture I attached you, from it, It is true that:

`(AB)/(A'B') =(BC)/(B'C')`

Hence:

`(12)/(6) =(21)/(x)`

Solving for x:

`x=(21)/(2) =10.5`