Can someone help me on my crossword puzzle

The blue segment below is a diameter of oo. what is the length of the radius of the circle?

Based on what you know about the location of the earth in relation to the sun, why is this called the goldilocks zone in other galaxies? a. it's a region that exhibits a weak gravitational pull, thus maintaining a safe distance from the sun. b. it's an area that doesn't experience any major weather events that could cause mass extinctions. c. it's an area that's an optimal distance from the sun for potentially supporting life. d. it's a region that's unaffected by asteroid or meteor impacts.

Avast plain of rolling hills are actually folds of monoclines domes and basins anticlines and synclines horsts and grabens