Find the Domain cos(2z)+sin(2z)=2
Problem
Solution
Identify the range of the trigonometric functions. For any real number
θ the functionscos(θ) andsin(θ) are bounded such that−1≤cos(θ)≤1 and−1≤sin(θ)≤1 Analyze the maximum possible value of the sum. The maximum value of the expression
cos(2*z)+sin(2*z) can be found using the identitya*cos(θ)+b*sin(θ)=√(,a2+b2)*cos(θ−ϕ) Calculate the maximum value. For
1⋅cos(2*z)+1⋅sin(2*z) the maximum value is√(,1+1)=√(,2) Compare the maximum value to the given equation. Since
√(,2)≈1.414 the maximum value of the left-hand side is less than2 Determine the solution set. Because
cos(2*z)+sin(2*z) can never reach the value2 for any realz there are no real solutions.Conclude the domain. The "domain" in the context of an equation usually refers to the set of values for which the expression is defined. Both
cos(2*z) andsin(2*z) are defined for all real numbers.
Final Answer
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