Article Diary - General Knowledge Digest

Pythagorean Identities

  1. sin²θ+ cos²θ = 1
  2. 1 + tan²θ = sec²θ
  3. 1 + cot²θ = csc ²θ

From (a) sin²θ = 1 − cos²θ i.e. cos²θ = 1 − sin²θ

These are called Pythagorean identities, because, as we will see in their proof, they are the trigonometric version of the Pythagorean theorem. The two identities are simply different versions of (a).

The first shows how we can express sin θ in terms of cos θ; the second shows how we can express cos θ in terms of sin θ.

Note: sin²θ "sine squared theta" means (sin θ)².

0 (0)
Article Rating (No Votes)
Rate this article
Attached Files
There are no attachments for this article.
There are no comments for this article. Be the first to post a comment.
Security Code Security Code
Related Articles RSS Feed
Scientific Terms Explained - N to Z
Viewed 2702 times since Sat, Dec 19, 2009
General Knowledge Quiz To Test Your General Knowledge
Viewed 2235 times since Sat, Nov 7, 2009
Scientific Terms and Meanings - Scientific Glossary Terms
Viewed 5501 times since Tue, Dec 15, 2009
Important Days in History
Viewed 2774 times since Sat, Dec 26, 2009
The Largest, Longest, Biggest, Highest, Smallest in the World
Viewed 3945 times since Mon, Dec 28, 2009
Largest, Smallest, Highest and Longest in India
Viewed 2570 times since Fri, Jan 15, 2010
Viewed 1258 times since Mon, Mar 22, 2010
Motorola Xoom Tablet with Android 3.0 Honeycomb OS
Viewed 1268 times since Wed, Jan 12, 2011
First People - Who were the first to do something?
Viewed 4627 times since Thu, Jan 14, 2010
Everyday Science Quiz Questions with Answers - Part 3
Viewed 2992 times since Mon, Dec 7, 2009