Can someone explain please

Answer:
Step-by-step explanation:
This might be familiar to you if you know about the pythagorean relationship in right triangle, aka pythagoras's theorem.
It states that, in a right triangle, the sum of the squares of the 2 shorter sides equals the square of the longest side, aka the hypotenuse.
Note that the triangle in this case is a right angled triangle, and all the surrounding shapes are squares.
So by the pythagorean relationship we have,
2^2 + 4^2 = c^2
4 + 16 = c^2
20 = c^2
c = sq root 20 = 2 * sq root 5
Hope it helps and if it does, plzzz mark me brainliest ;-)
Answer: 4.472
Step-by-step explanation: a squared + b squared = c squared then u get the square root of c