Hello there!
To start, you must find the the missing base length which can be found using
28/tan50 since you already know the length adjacent to the missing length and the angle measure of 50 (remember Tan = opposite side/adjacent side). When you simplify this, you should get that the measure of your base is approximately
23.49.
Now that you have your base, you can use it as well as your height of 28 to find the area of the triangle using A=1/2 base * height.
Plug in the values:
A=1/2(23.49)(28)
When you solve, you should get that the area of the triangle is approximately
328.86