For the base of the swimming pool:
You have the next figures as the sides:
The side number 1 and side 2 are retangles:
For the sides 3 and 4 you can draw the side as the sum of a recrtangle and a triangle:
Then, the area of this sides is the sum of the area of the rectangle and the area of the triangle:
You have the next figure as the base:
The area of a rectangle is:
L is length and w is width
To find the lenght you use the trangle formed in the side 3 and 4:
Pythagoras theorem:
Then, you have the next areas:Side 1:
Side 2:
Side 3:
Side 4:
Base:
The total area of the swimming pool is the sum of the areas above, approx. 407 sqare meters