I believe the answer is b
There is no real shortcut in learning integration formulas. You should take time learning and understanding how the formulas are derived until you are familiar with the formulas and you can easily recall the formulas. Hope this answers the question.
Answer:

Step-by-step explanation:
Given,
Side of the square

Therefore, area of the square = side × side



Answer: hypotenuse = 
Step-by-step explanation: Pythagorean theorem states that square of hypotenuse (h) equals the sum of squares of each side (
) of the right triangle, .i.e.:

In this question:
= 
2bc
Substituing and taking square root to find hypotenuse:

Calculating:


=
, then:


Hypotenuse for the right-angled triangle is
units