Solved on Feb 06, 2024

Solve the trigonometric equation 16cosx+10=1816 \cos x + 10 = 18 for 0x3600 \leq x \leq 360^{\circ}.

STEP 1

Assumptions
1. We are solving the equation 16cosx+10=1816 \cos x + 10 = 18.
2. The solution for xx must be within the interval 0x3600 \leq x \leq 360^{\circ}.

STEP 2

First, we need to isolate the cosine term. To do this, we subtract 10 from both sides of the equation.
16cosx+1010=181016 \cos x + 10 - 10 = 18 - 10

STEP 3

Simplify the equation to find the expression for cosx\cos x.
16cosx=816 \cos x = 8

STEP 4

Now, we divide both sides by 16 to solve for cosx\cos x.
16cosx16=816\frac{16 \cos x}{16} = \frac{8}{16}

STEP 5

Simplify the fraction on the right-hand side of the equation.
cosx=12\cos x = \frac{1}{2}

STEP 6

We now need to find the values of xx that satisfy the equation cosx=12\cos x = \frac{1}{2} within the interval 0x3600 \leq x \leq 360^{\circ}.

STEP 7

Recall that cosx=12\cos x = \frac{1}{2} has solutions in the first and fourth quadrants because cosine is positive in these quadrants.

STEP 8

Find the principal value of xx for which cosx=12\cos x = \frac{1}{2}. This is the value of xx in the first quadrant.
x=cos1(12)x = \cos^{-1}\left(\frac{1}{2}\right)

STEP 9

Calculate the principal value using the unit circle or a calculator.
x=60x = 60^{\circ}

STEP 10

Now find the value of xx in the fourth quadrant. Since cosine is symmetrical about the vertical axis, the angle in the fourth quadrant is 36060360^{\circ} - 60^{\circ}.

STEP 11

Calculate the angle in the fourth quadrant.
x=36060x = 360^{\circ} - 60^{\circ}

STEP 12

Simplify to find the second solution for xx.
x=300x = 300^{\circ}

STEP 13

We have found the two solutions for xx within the interval 0x3600 \leq x \leq 360^{\circ} that satisfy the equation cosx=12\cos x = \frac{1}{2}.
The solutions are x=60x = 60^{\circ} and x=300x = 300^{\circ}.

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