books.google.com - A perennial bestseller by eminent mathematician G. Polya, How to Solve It will show anyone in any field how to think straight. In lucid and appealing prose, Polya reveals how the mathematical method of demonstrating a proof or finding an unknown can be of help in attacking any problem that can be "reasoned"...https://books.google.com/books/about/How_to_Solve_It.html?id=X3xsgXjTGgoC&q=frustum&utm_source=gb-gplus-shareHow to Solve It