1. **State the problem:** We have a right triangle with base length 4 units and height $x$ units. The area of the triangle is given as 16 units². We need to find the missing length $x$. 2. **Formula for the area of a triangle:** $$\text{Area} = \frac{1}{2} \times \text{base} \times \text{height}$$ 3. **Apply the formula:** $$16 = \frac{1}{2} \times 4 \times x$$ 4. **Simplify the right side:** $$16 = 2 \times x$$ 5. **Solve for $x$:** $$x = \frac{16}{2}$$ 6. **Show cancellation:** $$x = \frac{\cancel{16}}{\cancel{2}} = 8$$ 7. **Final answer:** $$x = 8 \text{ units}$$ This means the height of the triangle is 8 units.