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
There Goes a... There Goes Santa Claus (1995) Dave and Becky pretend to be Santa Claus and do the duties that he does. Also, this episode is a flashback episode when Dave and Becky remember what they did in the past. 15. There Goes the Mail (or There Goes a Mail Truck) (1996) Letter Carriers Dave & Becky learn about where the mail goes and how it is transported. 16. There Goes a Rescue Vehicle (1996) Dave and Becky learn about different types of rescue work and the vehicles they use. 17. There Goes a Garbage Truck (1997) Dave and Becky learn about