Subscribe to our YouTube channel for the latest videos, updates, and tips.
We will learn how to find the expansion of cos (A + B + C). By using the formula of cos (α + β) and sin (α + β) we can easily expand cos (A + B + C).
Let us recall the formula of cos (α + β) = cos α cos β - sin α sin β and sin (α + β) = sin α cos β + cos α sin β.
cos (A + B + C) = cos [(A + B) + C]
= cos (A + B) cos C - sin (A + B) sin C, [applying the formula of cos (α + β)]
= (cos A cos B - sin A sin B) cos C - (sin A cos B + cos A sin B) sin C, [applying the formula of cos (α + β) and sin (α + β)]
= cos A cos B cos C - sin A sin B sin C - sin C sin A cos B - sin B sin C cos A, [applying distributive property]
= cos A cos B cos C (1 - tan A tan B - tan C tan A - tan B tan C)
Therefore, the expansion of cos (A + B + C) = cos A cos B cos C (1 - tan A tan B - tan C tan A - tan B tan C)
11 and 12 Grade Math
From Expansion of cos (A + B + C) to HOME PAGE
Didn't find what you were looking for? Or want to know more information about Math Only Math. Use this Google Search to find what you need.
May 20, 25 05:40 PM
May 19, 25 02:53 PM
May 18, 25 04:33 PM
May 17, 25 04:04 PM
May 17, 25 03:47 PM
New! Comments
Have your say about what you just read! Leave me a comment in the box below. Ask a Question or Answer a Question.