Bytelearn - cat image with glassesAI tutor

Welcome to Bytelearn!

Let’s check out your problem:

Which of the following is equivalent to 
sec ((pi)/(5)) ?

sec ((14 pi)/(5))

sec(-(pi)/(5))

sec ((6pi)/(5))

sec ((4pi)/(5))

Which of the following is equivalent to secπ5 \sec \frac{\pi}{5} ?\newlinesec14π5 \sec \frac{14 \pi}{5} \newlinesec(π5) \sec \left(-\frac{\pi}{5}\right) \newlinesec6π5 \sec \frac{6 \pi}{5} \newlinesec4π5 \sec \frac{4 \pi}{5}

Full solution

Q. Which of the following is equivalent to secπ5 \sec \frac{\pi}{5} ?\newlinesec14π5 \sec \frac{14 \pi}{5} \newlinesec(π5) \sec \left(-\frac{\pi}{5}\right) \newlinesec6π5 \sec \frac{6 \pi}{5} \newlinesec4π5 \sec \frac{4 \pi}{5}
  1. Properties of Secant Function: Understand the properties of the secant function. The secant function, sec(θ)\sec(\theta), is periodic with a period of 2π2\pi. This means that sec(θ)=sec(θ+2πk)\sec(\theta) = \sec(\theta + 2\pi k) for any integer kk. Additionally, sec(θ)=sec(θ)\sec(-\theta) = \sec(\theta) because secant is an even function.
  2. Evaluate First Option: Evaluate the first option, sec(14π5)\sec\left(\frac{14\pi}{5}\right). Since the secant function has a period of 2π2\pi, we can subtract 2π2\pi from 14π5\frac{14\pi}{5} until we are within the interval [0,2π)[0, 2\pi). 14π52π=14π510π5=4π5\frac{14\pi}{5} - 2\pi = \frac{14\pi}{5} - \frac{10\pi}{5} = \frac{4\pi}{5}. So, sec(14π5)\sec\left(\frac{14\pi}{5}\right) is equivalent to sec(4π5)\sec\left(\frac{4\pi}{5}\right).
  3. Evaluate Second Option: Evaluate the second option, sec(π5)\sec\left(-\frac{\pi}{5}\right). Since the secant function is even, sec(π5)\sec\left(-\frac{\pi}{5}\right) is equivalent to sec(π5)\sec\left(\frac{\pi}{5}\right).
  4. Evaluate Third Option: Evaluate the third option, sec(6π5)\sec\left(\frac{6\pi}{5}\right). Subtracting 2π2\pi from 6π5\frac{6\pi}{5} gives us 6π52π=6π510π5=4π5\frac{6\pi}{5} - 2\pi = \frac{6\pi}{5} - \frac{10\pi}{5} = -\frac{4\pi}{5}. Since secant is an even function, sec(4π5)\sec\left(-\frac{4\pi}{5}\right) is equivalent to sec(4π5)\sec\left(\frac{4\pi}{5}\right), which is not equivalent to sec(π5)\sec\left(\frac{\pi}{5}\right).
  5. Evaluate Fourth Option: Evaluate the fourth option, sec(4π5)\sec\left(\frac{4\pi}{5}\right). This is not equivalent to sec(π5)\sec\left(\frac{\pi}{5}\right) because 4π5\frac{4\pi}{5} is not equal to π5\frac{\pi}{5} plus any multiple of 2π2\pi.
  6. Compare Results: Compare the results from Steps 22, 33, 44, and 55. The only equivalent expressions to sec(π5)\sec\left(\frac{\pi}{5}\right) are sec(π5)\sec\left(-\frac{\pi}{5}\right) from Step 33 and sec(14π5)\sec\left(\frac{14\pi}{5}\right) from Step 22, which simplifies to sec(4π5)\sec\left(\frac{4\pi}{5}\right). However, since sec(4π5)\sec\left(\frac{4\pi}{5}\right) is not equivalent to sec(π5)\sec\left(\frac{\pi}{5}\right), there must be a mistake in the previous steps.

More problems from Write a formula for an arithmetic sequence