Math Forum - Ask Dr. Math

The Math Forum

$Ask Dr. Math - Questions and Answers from our Archives$ $_____________________________________________$
Associated Topics || Dr. Math Home || Search Dr. Math
$_____________________________________________$

Using the Laws of Sine and Cosine


Date: 9/24/95 at 20:45:58
From: Anonymous
Subject: trigonometry

How do I find the sine and cosine of pi/12?


Date: 9/24/95 at 21:38:59
From: Doctor Andrew
Subject: Re: trigonometry

Since pi/12 = pi/3 - pi/4 you can use the formulas:

cos(a+b) = cos(a)cos(b) - sin(a)sin(b)

sin(a+b) = sin(a)cos(b) + cos(a)sin(b)

with a = pi/3 and b = -pi/4.

Have a blast!

-Doctor Andrew,  The Geometry Forum

Associated Topics:
High School Trigonometry

Search the Dr. Math Library:

Find items containing (put spaces between keywords):

Click only once for faster results:

[ Choose "whole words" when searching for a word like age.]

all keywords, in any order at least one, that exact phrase
parts of words whole words

Submit your own question to Dr. Math

[Privacy Policy] [Terms of Use]

Math Forum Home || Math Library || Quick Reference || Math Forum Search
_____________________________________