Surds from tilted squares

Maths

Which of the values shown below is a surd?

What is the area of the tilted green square, in square units?

What's the area of the square below, in square units?

What's the length of one side of the square  shown below?

Which of the following squares has a surd side length?

What is the area of the square shown below, in square unit?

Finding the area of the surrounding shapes and subtracting it from the larger grid.

Splitting the square into smaller shapes, finding the area of each shape and adding them up.

Which is not a strategy for finding the area of a square on a grid?