Trigonometry (Continued)

Theorem 2

General solution of cos q = k

Method I

Let a be the least positive angle such that

Method II

Let a be the smaller positive angle with cos a = k.

Then, cos(-a) = k

cos q = cos a and cos (-a)

A = q or - a

Also, any co-terminal angle with above is trigonometrically equivalent and so has the same cosine.

q = (Any even multiple of p)+ a or (Any even multiple of p) - a

Particular Cases

ii) If cos q = 1, then cos a = 1, a = 0

= even multiple of p

= odd multiple of p

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	Introduction
	Co-terminal Angles
	Theorem 1
	Theorem 2
	Theorem 3
	Theorem 4
	Sine Formula (Sine Rule)
	Cosine Formula (Cosine Rule)
	Projection Formula
	Napier's Analogy
	Area of a triangle
	Hero's Formula
	Half-Angle Formulae
	Solution of triangles
	Heights and Distances
	Inverse Trigonometric Functions
	Summary
Animations
	Graphs of Inverse Trigonometric functions

Subjects
English
Math
Geometry