A problem by Syed Hamza Khalid

Well this problem can be simply solved with the sine rule

We can use the sine formula:

$\frac{a}{Sin A}$ = $\frac{b}{Sin B}$

In this case we have :

$\frac{x}{Sin 60}$ = $\frac{10}{Sin 40}$

Which can be simplified to:

$x$ = $\frac{10sin60}{Sin40}$

$=13.5cm$