You have 2 triangles here making up this single quadrilateral. One of the triangles is a 30-60-90 and the other one is a 45-45-90. These 2 triangles share a hypotenuse. We need the length of that hypotenuse if we are to find the missing side x. The "lower" triangle is the 30-60-90 and the side we are given is across from the 30 degree angle. In the Pythagorean triple for a 30-60-90, the side across from the 30 degree angle is x, the side across from the 60 degree angle is
![x √(3)](https://img.qammunity.org/2019/formulas/mathematics/college/zw531h1qa10f9zpp4s34ngrsgxmjdvve4x.png)
, and the hypotenuse is 2x. So we need to find x. If
![x=14 √(3)](https://img.qammunity.org/2019/formulas/mathematics/high-school/nuujeg7esyw41nhx1z17kzd1odqottzz66.png)
then two times x is equal to
![2(14 √(3))](https://img.qammunity.org/2019/formulas/mathematics/high-school/c26r9125kufm1a7hc7r4o9vsstqkc75660.png)
which is equal to
![28 √(3)](https://img.qammunity.org/2019/formulas/mathematics/high-school/50f5yvpjbl68r73t640wrk2wdgh0i53eru.png)
. So the length of the hypotenuse is
![28 √(3)](https://img.qammunity.org/2019/formulas/mathematics/high-school/50f5yvpjbl68r73t640wrk2wdgh0i53eru.png)
. The Pythagorean triple for a 45-45-90 is
![(x,x,x √(2))](https://img.qammunity.org/2019/formulas/mathematics/high-school/63gajjhhg93m6ji9byfwso8vau2cl8whio.png)
with
![x √(2)](https://img.qammunity.org/2019/formulas/mathematics/high-school/eu3g3dx15g4jwyc1kht1iust1jo5mbp4jd.png)
as the length of the hypotenuse in a 45-45-90. If the length of the hypotenuse is
![28 √(3)](https://img.qammunity.org/2019/formulas/mathematics/high-school/50f5yvpjbl68r73t640wrk2wdgh0i53eru.png)
, then we need to solve for x.
![x √(2)=28 √(3)](https://img.qammunity.org/2019/formulas/mathematics/high-school/isxjnwzpr31ooezz2qq44ijh4b6mlzok5k.png)
. We solve for x by dividing by the square root of 2, like this:
![x= (28 √(3) )/( √(2) )](https://img.qammunity.org/2019/formulas/mathematics/high-school/dnrfdw00kqjmh4duwlzyakrtmiz8lnxy8t.png)
. The only way to solve this is to multiply by
![( √(2) )/( √(2) )](https://img.qammunity.org/2019/formulas/mathematics/high-school/atecgciw16zwy03c1fx4xraoim8p1912l1.png)
. Doing this step by step we have
![(28 √(3) )/( √(2) )* ( √(2) )/( √(2) )](https://img.qammunity.org/2019/formulas/mathematics/high-school/b0uopgwph2jq0a6szmjn840khgb4ons8fy.png)
. Multiply straight across the top and straight across the bottom to get
![(28 √(6) )/(2)](https://img.qammunity.org/2019/formulas/mathematics/high-school/bfuj4ogtteqn431py16hh2x6poebks1s5w.png)
which simplifies by reduction to
![14 √(6)](https://img.qammunity.org/2019/formulas/mathematics/high-school/92o9u3ay323ij2u0ohhrhoxll20de8x78s.png)
. First choice above.