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Download cos 160 o 20 o is the reference angle for 160 o
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Trigonometry Section 7.4 Find the sine and cosine of special angles. Consider the angles 20o and 160o Note: sin 20o = sin160o and cos 20o = -cos 160o 20o is the reference angle for 160o The acute angle α is the reference angle for the angles, 180 – α, 180 + α, and 360 –α. Note: 20o is the reference angle for 160o , 200o , and 340o Find the reference angle 120o 190o 4 Express in terms of the reference angle sin 128o cos 128o sin -37o cos 5.2 Use a calculator to find each value sin 32o cos 107o sin 4.61 cos -6.42 Special triangles Find the indicated value sin 30o cos 60o sin 120o cos 135o sin 225o cos sin Graphs of trigonometric functions assignment • Page 279 • Problems 2 – 10 even, 11-20 all
