ANSWER
The third side of the triangle is 22.361 km
STEP-BY-STEP EXPLANATION:
Given information
The image given is a right-angled triangle
The perpendicular side = 10km
The adjacent side = 20km
To find the third side of the triangle, we will need to apply Pythagora's theorem
[tex]\text{Hypotenuse}^2=opposite^2+adjacent^2[/tex]
Let the hypotenuse be x
[tex]\begin{gathered} x^2=10^2+20^2 \\ x^2\text{ = 100+ 400} \\ x^2\text{ = 500} \\ \text{Take the sqyare roots of both sides} \\ x\text{ = }\sqrt[]{500} \\ x\text{ = 22.361 }km \end{gathered}[/tex]
Therefore, the third side of the triangle is 22.361 km
