Answer:
20
Step-by-step explanation:
Side of the square = hypotenuse of triangle = √(4² + 2²)=√(16 + 4)=√(20)
Area of a square = (side)² = (√20)² = 20 units²
first find missing side of triangle
a^2 + b^2 = c^2
4^2 + 2^2 = c^2
16+4=c^2
20=c^2
