5. What is the value of x?

Answer:
5[tex]\sqrt{3}[/tex]
Step-by-step explanation:
in a 30-60-90 triangle the ratio of sides, respectively, is 1 : [tex]\sqrt{3}[/tex] : 2
you can set up a proportion like this to solve for 'x':
[tex]\sqrt{3}[/tex] / 1 = 15 / x
cross-multiply:
[tex]\sqrt{3}[/tex]x = 15
x = 15/[tex]\sqrt{3}[/tex]
rationalize the denominator by multiply top and bottom by [tex]\sqrt{3}[/tex]
you get 15[tex]\sqrt{3}[/tex] ÷ 3 which is 5[tex]\sqrt{3}[/tex]