Solving of oblique triangles Case 1. Three sides a, b, c are given. Find angles A, B, C. By the law of cosines we find one of the angles: the second angle we find by the law of sines: the third angle is found by the formula: C = 180° – ( A + B ). E x a m p l e . Three sides of a triangle are given: a = 2, b = 3, c = 4. … [Read more...]

## Basic relations between elements of triangle

Basic relations between elements of triangle Law of cosines. Law of sines. Law of tangents. Area formulas. Heron's formula. Radii of circumscribed and inscribed circles. Designations: a, b, c – sides; A, B, C – angles of triangle; p = ( a + b + c ) / 2 - a half-perimeter; h – a height; S – an area; R, r – radii of circumscribed and inscribed circles … [Read more...]

## Some important correlations

Some important correlations Transforming product-to-sum. Universal substitution. Quadruple-angle formulas. The last three formulas are called a universal substitution; they are used at solving some of trigonometric equations and integrating of trigonometric functions. Back … [Read more...]

## Transforming of trigonometric expressions to product

Transforming of trigonometric expressions to product Back … [Read more...]

## Double- , triple-, and half-angle formulas

Double- , triple-, and half-angle formulas Signs before the roots are selected depending on the quarter, in which the angle is placed. Back … [Read more...]