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Trig 3.1: Trigonometric Identities. Definitions : Conditional equation —a statement that is true for a specific set of values Identity —an equation that is true for all real #’s in the domain. Fundamental Identities: 1. Reciprocal Identities:. 2. Quotient Identities:.
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Trig 3.1: Trigonometric Identities • Definitions: • Conditional equation—a statement that is true for a specific set of values • Identity—an equation that is true for all real #’s in the domain • Fundamental Identities: • 1. Reciprocal Identities:
2. Quotient Identities: 3. Pythagorean Identities: 4. Cofunction identities:
5. Even-Odd Identities: Even: Odd:
C. To simplify a trig expression, use algebra and these identities 1. Factoring: 1. Factor sec2 x – 1 2. Factor 4 tan2 x + tan x – 3 3. Factor csc2 x – cot x – 3 2. Complete: 4. sin x + cot x cos x 5. tan2 x sec2 x – tan2 x
Trig 3.2: Proving Identities A. Guidelines for Establishing Identities: 1. Work on one side of equation at a time 2. Look to factor, add fractions (LCD), use FOIL, or create a monomial denominator 3. Look to use fundamental identities 4. Perhaps try to convert all terms to sin and cos 5. Try something!!
Trig 3.3: Trigonometric Equations A. To Solve a Trig Equation: 1. Use algebra to isolate the trig function 2. Find the reference angle 3. Determine which quadrants is in on the interval 4. List solution(s)
B. To solve quadratic trig equations: 1. Use factoring and other algebra techniques to isolate functions 2. Substitute using identities if necessary 3. Solve over
Trig 3.4: Using Calculators A. Finding inverse functions using calculator: 1. Use 2ndsin-1, cos-1, tan-1 when trying to find an inverse function 2. Be sure calculator is in RADIAN mode 3. For cot-1, sec-1, csc-1 use the reciprocal of x <check quadrants carefully for cot-1 !!>
B. Solving trig equations -- calculator problem guidelines: 1. Use 2ndinverse function to determine the reference angle 2. Round to 3 decimal places 3. RADIAN mode 4. Use coterminal angles to list all solutions
Trig 3.5: Sum & Difference Formulas • Formulas for cosine: • Formulas for sine: • C. Formulas for tangent:
A. Double Angle Formulas: Trig 3.6: Double-Angle & Half-Angle Formulas
Trigonometry Unit 3 Test • Grademaster #1-30 (Name, Date, Subject, Period, Test Copy #) • Do Not Write on Test! Show All Work on Scratch Paper! • Label BONUS QUESTIONS Clearly on Notebook Paper. (If you have time) • Find Something QUIET To Do When Finished!