Q. Select the answer which is equivalent to the given expression using your calculator.cos(arctan3991)20399399203991201
Understand trigonometric functions: Understand the relationship between the trigonometric functions.The expression cos(arctan(x)) can be understood by considering a right triangle where x is the ratio of the opposite side to the adjacent side (tan=adjacentopposite). We need to find the cosine of the angle, which is the ratio of the adjacent side to the hypotenuse (cos=hypotenuseadjacent).
Apply relationship to expression: Apply the relationship to the given expression.Let's denote the angle whose arctan is 3991 as θ. So, tan(θ)=3991. In a right triangle, this means the opposite side is 1 and the adjacent side is 399. We need to find the hypotenuse using the Pythagorean theorem.
Use Pythagorean theorem: Use the Pythagorean theorem to find the hypotenuse.The Pythagorean theorem states that in a right triangle, the square of the hypotenuse c is equal to the sum of the squares of the other two sides a and b. So, c2=a2+b2.
Calculate hypotenuse: Calculate the hypotenuse.Let's calculate the hypotenuse c:c2=12+(399)2c2=1+399c2=400c=400c=20
Find cosine of angle: Find the cosine of the angle.Now that we have the adjacent side 399 and the hypotenuse 20, we can find cos(θ):cos(θ)=hypotenuseadjacentcos(θ)=20399
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