Chapter 9.2, Problem 42E

Solution

To calculate the given trigonometric function using calculator.

  $\sec \left(\frac{\pi }{9}\right)\approx 1.0642$

Given information:

  $\sec \left(\frac{\pi }{9}\right)$ .

Formula used:

• The trigonometric function of an angle $\theta$ of a right angled triangle $\Delta ABC$ are:

  $\sec \theta =\frac{hyp}{adj}$

Where opp is the opposite side to the angle $\theta$ , adj is the adjacent side to the angle $\theta$ , and hyp is the hypoten use of the triangle.

Calculation:

In order to find the value of the trigonometric function

  $\sec \left(\frac{\pi }{9}\right)$ using calculator, first make sure note that the calculator is in radian mode, if it is not then change it into radian mode.

Now type on calculator first press the trigonometric function “sec” button, and then type $\frac{\pi }{9}$ , and click “=” sign.

It will give the answer

  $\sec \left(\frac{\pi }{9}\right)\approx 1.0642$