(b) Solve the trigonometric equation and verify that its solutions are the x-coordinates of the maximum and minimum points of f. (Calculus is required to find the trigonometric equation. For each solution, give an exact answer and then round to four decimal places. Enter your answers from smallest to largest.)

The given trig equation is obtained by solving for the critical points of [tex]f[/tex], which is done by differentiating [tex]f[/tex] and setting the derivative equal to zero.

We have

[tex]18 \sin(x) \cos(x) - 9 \sin(x) = 0[/tex]

[tex]9 \sin(x) (2 \cos(x) - 1) = 0[/tex]

[tex]9 \sin(x) = 0 \text{ or } 2 \cos(x) - 1 = 0[/tex]

[tex]\sin(x) = 0 \text{ or } \cos(x) = \dfrac12[/tex]

In the interval [tex]0\le x< 2\pi[/tex], we have

[tex]\sin(x) = 0 \implies x = 0 \text{ or } x = \pi[/tex]

and

[tex]\cos(x) = \dfrac12 \implies x = \dfrac\pi3 \text{ or } x = \dfrac{5\pi}3[/tex]

In order from smallest to largest, that's

[tex]x = 0 \text{ or } x = \dfrac\pi3 \text{ or } x = \pi \text{ or } x = \dfrac{5\pi}3[/tex]

azikennamdi azikennamdi · Answer 2 · 2022-07-15T23:21:24+02:00

The solution to the Trigonometric equation is given as below.

What is a Trigonometric equation?

A trigonometric equation is one that involves one or more unknown trigonometric ratios. It is represented in terms of sine (sin), cosine (cos), tangent (tan), cotangent (cot), secant (sec), and cosecant (cosec) angles.

The solution to the above problem is?

The provided trigonometric equation is produced by determining the critical points of f by differentiating and setting the derivative to zero.

Thus,

18 sin (x) cos (x) - 9 sin (x) = 0

8 sin(x) = 0 or 2 cos (x) - 1 = 0

Sin (x) = 0 or Cos (x) = 1/2

Given the interval of 0 ≤ x ≤ 2π

→ Sin (x) = 0 → x = 0 or x = π

and

Cos (x) = 1/2

→ x = π/3 or x = 5π/3

Arranging the values from the smallest to the largest, we have:

x = 0 or x = π/3

x = π or x = 5π/3

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