Answer:
![x=28.32\ units](https://img.qammunity.org/2020/formulas/mathematics/middle-school/es2p61pi54blu0yipppxakc80lzigpfgml.png)
Explanation:
Given:
Expression for Pythagorean theorem:
![19^2+21^2=x^2](https://img.qammunity.org/2020/formulas/mathematics/middle-school/f4r7prdo6ozbmyebg34c5kdrzezfdl2joz.png)
By Pythagorean theorem (applied to right triangles only):
![c^2=a^2+b^2](https://img.qammunity.org/2020/formulas/mathematics/middle-school/xsm8kchig3pfblxfo10xa15jy2ias2waqf.png)
where
represents hypotenuse or the longest side of triangle, while
and
represents the other two sides of the triangle.
Solving for hypotenuse i.e.
in the given expression
![x^2=19^2+21^2](https://img.qammunity.org/2020/formulas/mathematics/middle-school/vn27wc49j49wwvfyuxg5650xttlal7n7bl.png)
⇒
![x^2=361+441](https://img.qammunity.org/2020/formulas/mathematics/middle-school/abtqknhd4sqadw58o4gp19m6fqkh1q24cm.png)
⇒
![x^2=802](https://img.qammunity.org/2020/formulas/mathematics/middle-school/nhb7l1ec70wghsssmy6kto7h4qby7ae8zs.png)
Taking square root both sides:
⇒
![√(x^2)=√(802)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/ay95fn7zs3upp2exsha6mx2o8kykk1816k.png)
∴
(Answer)