How do I solve this problem?

Answer:
5.3 cm
Step-by-step explanation:
[tex]area \: of \: \triangle = \frac{1}{2} \times base \times height \\ \\ 10.6 = \frac{1}{2} \times base \times 4 \\ \\ 10.6 = base \times 2 \\ \\ base = \frac{10.6}{2} \\ \\ base = 5.3 \: cm[/tex]