# NavList:

## A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

**Re: Request for simple trig formula**

**From:**Sam Chan

**Date:**2003 Apr 15, 18:19 -0700

Law of Cosine (good for non-right triangles) Let A, B, and C be the three angles of a triangle. Let a, b, and c be the lengths of the "opposite" side. The Law of Cosine: c^2 = a^2 +b^2 -2a*b*cos(C) For right triangles: Let C be the right angle. The long side opposite of C is called the hypotenuse. From any non-right angled corner, sin A = a/c where a is the length of the side opposite of the angle A and c is the hypotenuse cos A = b/c where b is the length of the side adjacent to the angle A and c is the hypotenuse Use either of these to find angle A. Once angle A is found, angle B =90-A. Sam ----- Original Message ----- From: "David Weilacher"To: Sent: Tuesday, April 15, 2003 3:03 AM Subject: Request for simple trig formula > I need a favor. > > I don't recall the simple trig formulas and don't have the mental where-with-all to find anything using a search engine. I think it is because my mind just doesn't index the way they do. > > If I know the lengths of 3 sides of a triangle and one angle (90), how do I determine the two remaining angles. > > I do own a fancy calculator capable of sin, cos stuff. > > What I would like to come away with are the side-angle-side, angle-side-angle, and side-side-side formulas so that I can write them down in my address book for future reference. > > Thank you. > > PS: I am attempting to solve a problem indirectly related to navigation. > > > Dave Weilacher > .US Coast Guard licensed captain > . #889968 > .ASA instructor evaluator and celestial > . navigation instructor #990800 > .IBM AS400 RPG contract programmer