McGraw Hill Glencoe Algebra 2, 2012
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McGraw Hill Glencoe Algebra 2, 2012 View details
Standardized Test Practice

Exercise 12 Page 915

Consider each side of the equation as a function. Graph both functions on the same coordinate plane and look for points of intersection.

t≈ 2.52

Practice makes perfect

To solve the given equation in the interval from 0 to 2π, we will consider both sides of the equation as functions. Then, we will graph both of them on the same coordinate plane. 3cos t/3= 2 ⇓ y= 3cos t/3 and y= 2 Before graphing the functions, note that the amplitude of the cosine function is 3. Also, we want to find solutions between 0 and 2π ≈ 6.28. Accordingly, let's resize the window of the calculator to show y-values between - 3.5 and 3.5, and x-values between 0 and 6.28. To do so, we will push WINDOW and change the settings.

Now, let's graph both functions. The x-coordinate of the points of intersection, if any, will be the solutions to the equation. Press the Y= button and type the functions in the first two rows. Having written the functions, push GRAPH to draw them.

We can see that there is one point of intersection. To find this, push 2nd and CALC and choose the fifth option, intersect.

While using the intersect tool, we are asked to select the first function, the second function, and to make a guess for the approximate point of intersection. Because there is only one point of intersection between these two functions, we can just start with any point in our domain, that is from 0 to 2Ï€.

The point of intersection is approximately 2.523206, which we will round to be t≈ 2.52. We also see, that there are no more intersections in the given domain. t≈ 2.52

Checking Our Answer

Checking the Answer
We can check our solution by substituting it for t in the given equation. Be aware that since the solution is not exact, we will obtain an approximation. Let's substitute t≈ 2.52.

3cos t/3 = 5

t ≈ 2.52

3t/3 ? ≈ 2
2.002388 ≈ 2 ✓

Since we obtained a true statement, we know that the solution is correct.