Bookmarks by Tapas Rakshit https://padlet.com/tapasridm13/Bookmarks Made with a quick smile en-us 2022-02-10 07:01:36 UTC 2023-03-18 06:04:34 UTC hello@padlet.com Mathematics tapasridm13 https://padlet.com/tapasridm13/Bookmarks/wish/2039722755 Trigonometry  is a branch of mathematics that studies relationships between side lengths and angles of triangles.The Greeks focused on the calculation of chords, while mathematicians in India created the earliest-known tables of values for trigonometric ratios (also called trigonometric functions) such as sine.
Trigonometry is known for its many identities. These trigonometric identities are commonly used for rewriting trigonometrical expressions with the aim to simplify an expression, to find a more useful form of an expression, or to solve an equation.(ref:Wikipedia)
The basic relationship between the sine and cosine is given by the Pythagorean identity: where sinA  = P/H ; cosA = B/H ; tanA = P/B; other 3 i.e. cosecA,secA & cotA are reciprocal of sinA,cosA and tanA respectively ( or follow the table)( H is the side opposite to 90°, B is the side adjacent to angle A & P is side opposite to angle A) sin^{2}theta+cos ^{2}theta =1,
where sin ^{2}theta  means 
{sin (theta )}^{2} 
and {cos ^{2}theta } means {cos theta )^{2}.
This can be viewed as a version of the Pythagorean theorem, and follows from the equation {x^{2}+y^{2}=1} for the unit circle. This equation can be solved for either the sine or the cosine:
where the sign depends on the quadrant of theta .
Dividing this identity by {sin ^{2}theta }, {cos ^{2}\theta }, or both yields the following identity 

1+cot ^{2}theta =cosec ^{2}theta

{tan ^{2}theta +1=sec ^{2}theta }

{sec ^{2}theta + cosec ^{2}theta = sec ^{2}theta X cosec ^{2}theta.


]]> 2022-02-10 08:13:22 UTC https://padlet.com/tapasridm13/Bookmarks/wish/2039722755 Trigonometry 2 tapasridm13 https://padlet.com/tapasridm13/Bookmarks/wish/2040134300 2022-02-10 12:48:53 UTC https://padlet.com/tapasridm13/Bookmarks/wish/2040134300