Trigonometry Examples

Solve for x 4cos(x)^2-4sin(x)-5=0
Step 1
Replace the with based on the identity.
Step 2
Simplify each term.
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Step 2.1
Apply the distributive property.
Step 2.2
Multiply by .
Step 2.3
Multiply by .
Step 3
Subtract from .
Step 4
Substitute for .
Step 5
Factor the left side of the equation.
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Step 5.1
Factor out of .
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Step 5.1.1
Factor out of .
Step 5.1.2
Factor out of .
Step 5.1.3
Rewrite as .
Step 5.1.4
Factor out of .
Step 5.1.5
Factor out of .
Step 5.2
Factor using the perfect square rule.
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Step 5.2.1
Rewrite as .
Step 5.2.2
Rewrite as .
Step 5.2.3
Check that the middle term is two times the product of the numbers being squared in the first term and third term.
Step 5.2.4
Rewrite the polynomial.
Step 5.2.5
Factor using the perfect square trinomial rule , where and .
Step 6
Divide each term in by and simplify.
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Step 6.1
Divide each term in by .
Step 6.2
Simplify the left side.
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Step 6.2.1
Dividing two negative values results in a positive value.
Step 6.2.2
Divide by .
Step 6.3
Simplify the right side.
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Step 6.3.1
Divide by .
Step 7
Set the equal to .
Step 8
Solve for .
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Step 8.1
Subtract from both sides of the equation.
Step 8.2
Divide each term in by and simplify.
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Step 8.2.1
Divide each term in by .
Step 8.2.2
Simplify the left side.
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Step 8.2.2.1
Cancel the common factor of .
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Step 8.2.2.1.1
Cancel the common factor.
Step 8.2.2.1.2
Divide by .
Step 8.2.3
Simplify the right side.
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Step 8.2.3.1
Move the negative in front of the fraction.
Step 9
Substitute for .
Step 10
Take the inverse sine of both sides of the equation to extract from inside the sine.
Step 11
Simplify the right side.
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Step 11.1
The exact value of is .
Step 12
The sine function is negative in the third and fourth quadrants. To find the second solution, subtract the solution from , to find a reference angle. Next, add this reference angle to to find the solution in the third quadrant.
Step 13
Simplify the expression to find the second solution.
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Step 13.1
Subtract from .
Step 13.2
The resulting angle of is positive, less than , and coterminal with .
Step 14
Find the period of .
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Step 14.1
The period of the function can be calculated using .
Step 14.2
Replace with in the formula for period.
Step 14.3
The absolute value is the distance between a number and zero. The distance between and is .
Step 14.4
Divide by .
Step 15
Add to every negative angle to get positive angles.
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Step 15.1
Add to to find the positive angle.
Step 15.2
To write as a fraction with a common denominator, multiply by .
Step 15.3
Combine fractions.
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Step 15.3.1
Combine and .
Step 15.3.2
Combine the numerators over the common denominator.
Step 15.4
Simplify the numerator.
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Step 15.4.1
Multiply by .
Step 15.4.2
Subtract from .
Step 15.5
List the new angles.
Step 16
The period of the function is so values will repeat every radians in both directions.
, for any integer