130 likes | 317 Views
Chapter 7. Trigonometric Identities and Equations. 7.1 Basic Trigonometric Identities. Reciprocal Identities. These identities are derived in this manner sin = and csc = which gives you sin =. Quotient Identities.
E N D
Chapter 7 Trigonometric Identities and Equations
Reciprocal Identities These identities are derived in this manner sin = and csc = which gives you sin =
Quotient Identities If using a unit circle as reference, these identities were derived using = = tan
Tips For Verifying Trig Identities • Simplify the complicated side of the equation • Use your basic trig identities to substitute parts of the equation • Factor/Multiply to simplify expressions • Try multiplying expressions by another expression equal to 1 • REMEMBER to express all trig functions in terms of SINE AND COSINE
Difference Identity for Cosine Cos (a – b) = cosacosb + sinasinb • As illustrated by the textbook, the difference identity is derived by using the Law of Cosines and the distance formula
Sum Identity for Cosine Cos (a+b) = cos (a- (-b)) The sum identity is found by replacing -b with b *Note* If a and b represent the measures of 2 angles then the following identities apply: cos (a±b) = cosacosb±sinasinb
Sum/Difference Identity For Sine sinacosb + cosasinb= sin(a + b) – sum identity for sine If you replace b with (-b) you can get the difference identity of sine. sin (a – b) = sinacosb - cosasinb
Sum & Difference Tan[a ± b] = This identity is used as both the sum and difference identity.