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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

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