How do you determine the missing lenght

What is the approximate circumference of the circle shown below? 12.2 cm

Which characteristics are true of the arabian desert? multiple answers choose all answers that are correct. a. is mostly below sea level b. covers almost the entire arabian peninsula c. contains the largest sand sea in the world d. has very few people living there

Read the article titled "trans-saharan migration routes to north africa and the eu: historical roots and current trends." why do tens of thousands of sub-saharan africans try to cross the mediterranean each year? how are these refugees commonly portrayed? (site 1)