Area of a circle "ds" over the whole circle formula_33 is just the arc length, which is its circumference, so this shows that the area "A" enclosed by the circle is equal to formula_34 times the circumference of the circle. Note that the area of a semicircle of radius r can be computed by the integral formula_35. By trigonometric substitution, we substitute formula_36, hence formula_37 The last step follows since the trigonometric identity formula_42 implies that formula_43 and formula_44 have equal integrals over the interval formula_45, using integration by substitution. But on the other hand, since formula_46, the sum of the two integrals is
Straight from the Hart Straight from the Hart Straight from the Hart is a 2011 autobiography by Canadian professional wrestler Bruce Hart. The book chronicles Hart's childhood in Calgary as a member of the Albertan Hart wrestling family, his career in the wrestling industry to his later life as a trainer. It was published by ECW Press. The book is one of a long line of books by or about members of Hart's family. The book was first announced in May 2010. In March Hart was interviewed about the book on WDFN Wrestling Elite and Monday Night Mayhem. On Monday Night Mayhem Hart explained