Question

find the missing length of the triangle. 20 km 21 km c

Explanation:

Step1: Identify the formula

Use the Pythagorean theorem $a^{2}+b^{2}=c^{2}$ for a right - triangle, where $a = 20$ km, $b = 21$ km and $c$ is the hypotenuse.

Step2: Substitute values

Substitute $a = 20$ and $b = 21$ into the formula: $20^{2}+21^{2}=c^{2}$. Calculate $20^{2}=400$ and $21^{2}=441$. Then $400 + 441=c^{2}$, so $c^{2}=841$.

Step3: Solve for $c$

Take the square root of both sides. Since $c>0$ (as it represents a length), $c=\sqrt{841}=29$ km.

Answer:

$29$ km