How is the relationship between diameter and radius expressed?

Fiona and her friends are playing a game by guessing where a coin will land when it is randomly dropped inside the square shown below. fiona guesses that the coin is likely to land in the blue area. which explains whether or not fiona is correct and why?

Find the area of the triangle shown 3 by 6

What is the best approximation for the area of a circle with a radius of 4 m ? use 3.14 to approximate pi