Sum and Difference Identities definitions Flashcards
Sum and Difference Identities definitions
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Sum and Difference Identities Formulas that express trig functions of sums or differences of angles in terms of functions of individual angles. Sine Sum Identity Formula expanding the sine of a sum into products of sines and cosines of the individual angles. Sine Difference Identity Formula expanding the sine of a difference into products of sines and cosines of the individual angles, with a sign change. Cosine Sum Identity Formula expressing the cosine of a sum as the difference of products of cosines and sines of the angles. Cosine Difference Identity Formula expressing the cosine of a difference as the sum of products of cosines and sines of the angles. Tangent Sum Identity Formula expressing the tangent of a sum as a quotient involving the tangents of the individual angles. Tangent Difference Identity Formula expressing the tangent of a difference as a quotient involving the tangents of the individual angles, with sign changes. Unit Circle A circle of radius one centered at the origin, used to define exact values of trig functions for standard angles. Quadrant One of four regions in the coordinate plane, used to determine the sign of trig values based on angle location. Cofunction Identity Relationship showing how trig functions of complementary angles are related, often verified using sum and difference identities. Verification Process of simplifying one or both sides of a trig equation to show equality, often using identities. Pythagorean Theorem Relationship among the sides of a right triangle, used to find missing side lengths when solving trig problems. Exact Value A non-decimal, simplified result for a trig function, often involving radicals or fractions, not approximated numerically. Special Right Triangle A triangle with angle measures and side ratios that are commonly used to quickly find trig values. Argument The angle or expression inside a trig function, which may be a sum or difference of two angles.