Answer: 511cm*2
Explanation:
To find the area of a figure with sides of 38cm, 16cm, 20cm, and 18cm, we can use Heron's formula to calculate the area of the two triangles formed by drawing a diagonal. The area of each triangle can be found by using the formula A=1/2 x b x h, where b is the base and h is the height. The formulas for semiperimeter and area using Heron's formula are given in [1]. Using these formulas, we can find the area of each triangle and then add them together to find the area of the quadrilateral. Adding 13 to the final answer will give us the total area, as explained in [2]. The final answer is 511cm^2.