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.

Attached Files
There are no attachments for this article.
Comments
There are no comments for this article. Be the first to post a comment.
Name
Email
Security Code Security Code
Related Articles RSS Feed
Medical Inventions and Discoveries
Viewed 2384 times since Fri, Jan 15, 2010
Everyday Science Quiz Questions with Answers - Part 3
Viewed 2037 times since Mon, Dec 7, 2009
Branches of Science and their Definitions
Viewed 4702 times since Sat, Dec 26, 2009
The Largest, Longest, Biggest, Highest, Smallest in the World
Viewed 2822 times since Mon, Dec 28, 2009
Latest Inventions & Discoveries in Science
Viewed 2324 times since Tue, Jan 12, 2010
Capital of Countries
Viewed 2455 times since Thu, Dec 24, 2009
Famous Characters in Literature
Viewed 2907 times since Tue, Dec 8, 2009
Terminology - Study of terms and their use
Viewed 2226 times since Wed, Dec 30, 2009
AIEEE 2010 Answer Key - Download AIEEE 2010 Solved Paper
Viewed 1931 times since Mon, Apr 26, 2010
Units of Measurement
Viewed 1904 times since Sat, Dec 19, 2009
MENU