Textbook Question
Use the identities for the cosine of a sum or difference to write each expression as a trigonometric function of θ alone.
cos(θ - 270°)
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Use the identities for the cosine of a sum or difference to write each expression as a trigonometric function of θ alone.
cos(θ - 270°)
Simplify each expression. See Example 4.
cos² 2x - sin² 2x
Verify that each equation is an identity.
(sin 2x)/(2sin x) = cos² (x/2) - sin² (x/2)
Verify that each equation is an identity.
cot² (x/2) = (1 + cos x)²/(sin² x)
Write each function as an expression involving functions of θ or x alone. See Example 2.
sin(π + x)
Use the identities for the cosine of a sum or difference to write each expression as a trigonometric function of θ alone.
cos(90° + θ)