books.google.com - Multiply your chances of success on the ACT Math TestThe ACT Mathematics Test is a 60-question, 60-minute subtest designed to measure the mathematical skills students have typically acquired in courses taken by the end of 11th grade, and is generally considered to be the most challenging section of the...http://books.google.com/books/about/ACT_Math_For_Dummies.html?id=vJmZd2Gxrb0C&q=radius&utm_source=gb-gplus-shareACT Math For Dummies