Hello. This is my first post. I just started physics this year, and I forgot how to do some simple trigonometry, but I'm not quite sure where to look. 1. My question is: If I know the circumference of the Earth at the Equator is about 2.49 x 10 to the Fourth, How do I find the Circumference of the Earth 45 Degrees North? 2. Relevant equations: None 3. None... Obviously it would be smaller, but I'm not quite sure how much. Thanks for the help.