Question

what is the missing length? area of shaded region = 12 km² a = kilometers

Explanation:

Step1: Recall triangle - area formula

The area formula for a triangle is $A=\frac{1}{2}\times base\times height$. Here, the base is 6 km and the height is $a$, and $A = 12$ km².

Step2: Substitute values into formula

We have $12=\frac{1}{2}\times6\times a$.

Step3: Solve for $a$

First, simplify the right - hand side: $\frac{1}{2}\times6\times a = 3a$. So the equation becomes $3a=12$. Then divide both sides by 3: $a=\frac{12}{3}=4$.

Answer:

4