Q. Which of the following is not equivalent to csc72π ?csc(−712π)csc716πcsc712πcsc719π
Properties and Periodicity: Understand the properties of the cosecant function and periodicity.The cosecant function, csc(θ), is the reciprocal of the sine function, sin(θ), and has a period of 2π. This means that csc(θ+2πk)=csc(θ) for any integer k.
Analyze Option 1: Analyze the first option csc(−712π). Using the property that csc(−θ)=−csc(θ) and the periodicity of the cosecant function, we can find an equivalent angle in the positive direction by adding 2π until we get a positive angle. csc(−712π)=csc((2π−712π)+2πk) for k=1, since we want the smallest positive coterminal angle. \csc\left(-\frac{\(12\) \pi}{\(7\)}\right) = \csc\left(\left(\frac{\(14\)\pi}{\(7\)} - \frac{\(12\)\pi}{\(7\)}\right) + \frac{\(14\)\pi}{\(7\)}\right) = \csc\left(\left(\frac{\(2\)\pi}{\(7\)}\right) + \frac{\(14\)\pi}{\(7\)}\right) = \csc\left(\frac{\(16\)\pi}{\(7\)}\right)
Analyze Option \(2: Analyze the second option csc(716π). Using the periodicity of the cosecant function, we can subtract 2π to find an equivalent angle. csc(716π)=csc(716π−2π)=csc(716π−714π)=csc(72π) This is equivalent to the original expression csc(72π).
Analyze Option 3: Analyze the third option csc(712π). Using the periodicity of the cosecant function, we can subtract 2π to find an equivalent angle. csc(712π)=csc(712π−2π)=csc(712π−714π)=csc(−72π) Since csc(−θ)=−csc(θ), this is not equivalent to csc(72π) because the cosecant function is not an even function.
Analyze Option 4: Analyze the fourth option csc(719π). Using the periodicity of the cosecant function, we can subtract 2π multiple times to find an equivalent angle. csc(719π)=csc(719π−2π)=csc(719π−714π)=csc(75π) This is not equivalent to csc(72π) because 75π is not a coterminal angle of 72π.
Determine Non-equivalent Option: Determine which option is not equivalent to csc(72π). From the previous steps, we have determined that csc(716π) and csc(−712π) are equivalent to csc(72π). However, csc(712π) simplifies to csc(−72π), which is not equivalent to csc(72π). Therefore, csc(712π) is not equivalent to csc(72π).
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