Euclid's Elements is a mathematical and geometric treatise consisting of 13 books attributed to the ancient Greek mathematician Euclid in Alexandria, Ptolemaic Egypt circa 300 BC. It is a collection of definitions, postulates (axioms), propositions (theorems and constructions), and mathematical proofs of the propositions. The books cover Euclidean geometry and the ancient Greek version of elementary number theory. The work also includes an algebraic system that has become known as geometric algebra, which is powerful enough to solve many algebraic problems, including the problem of finding the square root of a number. Elements is the second-oldest extant Greek mathematical treatise after Autolycus' On the Moving Sphere, and it is the oldest extant axiomatic deductive treatment of mathematics. It has proven instrumental in the development of logic and modern science. According to Proclus, the term "element" was used to describe a theorem that is all-pervading and helps furnishing proofs of many other theorems. The word 'element' in the Greek language is the same as 'letter'. This suggests that theorems in the Elements should be seen as standing in the same relation to geometry as letters to language. Later commentators give a slightly different meaning to the term element, emphasizing how the propositions have progressed in small steps, and continued to build on previous propositions in a well-defined order.

#1 New York Times and Globe and Mail bestselling author Louse Penny's beloved Chief Inspector Armand Gamache mystery novels have received critical acclaim, won numerous awards, and have enthralled millions of readers. Featuring Chief Inspector of Homicide Armand Gamache of the Sûreté du Québec, these extraordinary novels are here together for the first time in a fabulous ebook bundles. A Trick of the Light When Three Pines artist Clara Morrow's former friend is found dead in her garden, Chief Inspector Gamache finds the art world is one of shading and nuance, shadow and light. And even when facts are slowly exposed, it is no longer clear to Gamache and his team if what they've found is the truth, or simply a trick of the light. The Beautiful Mystery No outsiders are ever admitted to the monastery of Saint-Gilbert-Entre-les-Loups, where the monks have become world-famous for their glorious chants. But when the renowned choir director is murdered, the lock is drawn back to admit Chief Inspector Gamache. Before he can find the killer, the Chief must first consider the divine, the human, and the cracks in between. How the Light Gets In As Christmas approaches, Chief Inspector Gamache travels to Three Pines as a favor to the bookshop owner, whose friend has gone missing—a friend who was once one of the most famous people in the world. With mounting crises in his own homicide department, Gamache finds himself not only investigating a murder, but also seeking refuge for himself and his still-loyal colleagues—if such a refuge exists.

The Secret Seven are siblings Peter and Janet, and Jack, Barbara, Pam, Colin and George. Together they are The Secret Seven - ready to solve any mystery, any time. Books 7-9 in Enid Blyton's classic series are brought together in this three-book collection. Book 7: Secret Seven Win Through (first published in 1955) The Seven have a fantastic new hiding place. But someone else is using it at night - and it's Jack's little sister Susie who helps them catch the intruder. Book 8: Three Cheers, Secret Seven (first published in 1956) Peter and Jack see a gas-fire alight in one of the rooms when they search for their lost aeroplane in the garden of an abandoned house. Who is hiding there and why? Book 9: Secret Seven Mystery (first published in 1957) A girl runs away from home - and it's up to the Seven to find her! Jack's little sister Susie is up to her usual tricks - but she can't put the Seven off the trail of clues! This collection features the original black and white illustrations throughout.

"Funny, adorable, and action-packed!" —Kazu Kibuishi, #1 New York Times bestselling creator of the Amulet series From the creator of the Bird & Squirrel graphic novel series, comes this hilarious and action-packed new series which follows a feline secret agent who will do whatever it takes to save the world—even if it means destroying a few things along the way. The Super-Secret Spy Service’s mission is to keep the world safe from maniacal villains. And Agent 9 is one of its best operatives. Although Nine always manages to complete the mission, there is occasionally some collateral damage (like the priceless Pigasso painting that was destroyed while foiling an art heist). So Agent 9 is now on probation. But when bumbling supervillain King Crab manages to overtake S4 head­quarters, there is no one else to turn to. Nine—along with a robotic partner named FiN—is all that stands between King Crab and his diabolical plans to melt the polar ice caps and build a massive water park. Can Agent 9 prove to be the right cat for the job by overcoming impulsive behavior and saving the world from a complete flood-a-geddon?

New threats, new foes...and a new partner?! This hilarious, action-packed spy series—from the creator of Bird & Squirrel—is perfect for readers who love funny crime-fighting stories like The InvestiGators, The Bad Guys, and Dog Man! Agent 9 is back in action at the Super-Secret Spy Service, and it couldn’t come at a better time. The next assignment? Stopping the Wolf, a cunning canine who’s been hired by the sinister organization DiViSiON to hunt down the final pieces of a mind-control device. It’s a mission of such paramount importance that Nine must do the unthinkable—work with a partner! S4 teams up Agent 9 with Traps, a mouse who specializes in covert operations (and knitting too). Unfortunately, the partnership gets off to a rocky start. And despite their best efforts, the Wolf always seems to be one step ahead. With time running out and DiViSiON’s plans to take over the world nearly complete, can Nine overcome the toughest challenge yet: being part of a team?