The region is made up of
• a right triangle with short leg 10 m and hypotenuse 26 m
• a parallelogram with sides 40 m and 26 m (the 26-m side corresponds to the aforementioned hypotenuse)
• another triangle with two known legs of length 20 m and 26 m
Find the height of the right triangle using the Pythagorean theorem. If the height is h, then
(10 m)² + h² = (26 m)² ⇒ h² = 576 m² ⇒ h = 24 m
This height is common to all three shapes.
Now find the area of each shape.
• right triangle:
1/2 × (10 m) × (24 m) = 120 m²
• parallelogram:
(40 m) × (24 m) = 960 m²
• other triangle:
• 1/2 × (20 m) × (24 m) = 240 m²
Then the total area of the shaded region is 1320 m².