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### Evaluating Trigonometric Functions Using Technolo…

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University of Southern California

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Problem 26

Evaluating Trigonometric Functions Using Technology
In Exercises $25-28$ , use a calculator to evaluate each trigonometric function. Round your answers to four decimal places.
$$\begin{array}{l}{\text { (a) } \sec 225^{\circ}} \\ {\text { (b) } \sec 135^{\circ}}\end{array}$$

(a) $\sec \left(225^{\circ}\right)=-1.4142$
(b) $\sec \left(135^{\circ}\right)=-1.4142$

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## Video Transcript

we are asked to use our calculators to evaluate the following to trigger a metric functions and then to round our answer to four decimal places. Now, this question is pretty straightforward. One important thing we need to remember is that when we look at our calculator over here, we're not able to find that c can't function. And that's because most calculators don't show C can't Cosi cantor co tangent. Therefore, we're going to need to use our base Trigana metric functions to find C can't now C can't Fada is the exact same thing expressed in our base. Trigonometry functions as one over CO St data, and with that piece of information, we should be able to completely solve this problem. All you need to dio is for party right? One over co sign of 225 degrees equals. Plug that into a calculator and you're going to find that equals negative one point for 14 2136 depending on how accurate your calculator is now, around this 24 decimal places, we look at the four digits following that and we look at the fifth since the fifth is less than five. It's the one we can simply say that this equals negative. One point for one floor. Two, All right, And so that's the answer for C can't of 225 degrees. All right, so that was party Now moving on to Part B, you'll use the exact same process. You're just going to take one over co sign of 135 degrees. Plug that into a calculator, and you're going to find that it's actually the exact same answers We've gotten party negative one 0.41 for two on 36 And then, just to make it very clear you need around that 24 decimal places. So then that's your answer. Yeah, and so you'll notice that these are both the same. And that's because their differences 90 degrees and so seeking up 225 equal seeking of 135. All right, And that let me circle the answer, and that's all