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Material Type: Assignment; Class: Plane Trigonometry; Subject: Mathematics Main; University: University of Arizona; Term: Unknown 1989;
Typology: Assignments
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Math 111, Supplemental Assignment #5 (Negative Angle Identities) Set your calculator in radian mode. Round answers to 2 decimal places. Part I: The negative angle identity for the cosine function Plot all points on the set of coordinate axes below. Each (x,y) point comes from an equation cos x = y. Find cos 0 = _____, cos .2 = _____, cos (-.2) = _____. Plot all three of these points. Find cos .6 = _____ and cos (-.6) = _____. Plot these two points. Find cos 1 = _____ and cos (-1) = _____. Plot these two points. Find cos 2 = _____ and cos 2 = _____. Plot these two points. Find cos 2 = _____ and cos (-2) = _____. Plot these two points. If cos 3 = n, then what is cos (-3)? How are cos 3 and cos (-3) related? (Write an equation.) For any number x, ifcos x = m, what is cos (-x)? Write an equation relating cos x and cos (-x). This is the negative angle identity for the cosine function. On your calculator graph Y1 = cos (x) and Y2 = cos(-x). How many graphs do you see? What does this suggest about the relationship between cos x and cos (-x)? Consider the single graph y = cos x. The graph has what type of symmetry? Such graphs represent even functions.
Part II: Sine function Graph Y1 = sin x and Y2 = sin (-x) on your calculators. How many graphs do you see? Do you think that sin x = sin (-x)? Find sin .2 = _____ and sin (-.2) = _____. How do sin .2 and sin (-.2) relate to each other? (Write an equation.) Find sin .4 = _____. Without using your calculator, make a conjecture (guess) about the value of sin (-.4) = _____. Use your calculator to determine whether your conjecture is correct. For any number x, how do sin x and sin (-x) relate to each other? (Write an equation.) What kind of symmetry does the graph of y = sin x have? Such graphs are called odd functions. Part III: Tangent function We know that tan x = (^) x x cos sin
terms of sin (-x) and cos (-x). Use negative angle identities for sin (-x) and cos (-x) to rewrite the equation in terms of sin x and cos x. Write the negative angle identity for the tangent function. Recall that n m = n m (^). tan (-x) = _____ The function y = tan x is what type of function (choose one): odd, even, neither. What type of symmetry does the graph of y = tan x have?