Trigonometry Examples

Solve for θ in Degrees tan(theta)^2+6tan(theta)+8=0
Step 1
Factor the left side of the equation.
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Step 1.1
Let . Substitute for all occurrences of .
Step 1.2
Factor using the AC method.
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Step 1.2.1
Consider the form . Find a pair of integers whose product is and whose sum is . In this case, whose product is and whose sum is .
Step 1.2.2
Write the factored form using these integers.
Step 1.3
Replace all occurrences of with .
Step 2
If any individual factor on the left side of the equation is equal to , the entire expression will be equal to .
Step 3
Set equal to and solve for .
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Step 3.1
Set equal to .
Step 3.2
Solve for .
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Step 3.2.1
Subtract from both sides of the equation.
Step 3.2.2
Take the inverse tangent of both sides of the equation to extract from inside the tangent.
Step 3.2.3
Simplify the right side.
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Step 3.2.3.1
Evaluate .
Step 3.2.4
The tangent function is negative in the second and fourth quadrants. To find the second solution, subtract the reference angle from to find the solution in the third quadrant.
Step 3.2.5
Simplify the expression to find the second solution.
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Step 3.2.5.1
Add to .
Step 3.2.5.2
The resulting angle of is positive and coterminal with .
Step 3.2.6
Find the period of .
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Step 3.2.6.1
The period of the function can be calculated using .
Step 3.2.6.2
Replace with in the formula for period.
Step 3.2.6.3
The absolute value is the distance between a number and zero. The distance between and is .
Step 3.2.6.4
Divide by .
Step 3.2.7
Add to every negative angle to get positive angles.
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Step 3.2.7.1
Add to to find the positive angle.
Step 3.2.7.2
Subtract from .
Step 3.2.7.3
List the new angles.
Step 3.2.8
The period of the function is so values will repeat every degrees in both directions.
, for any integer
, for any integer
, for any integer
Step 4
Set equal to and solve for .
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Step 4.1
Set equal to .
Step 4.2
Solve for .
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Step 4.2.1
Subtract from both sides of the equation.
Step 4.2.2
Take the inverse tangent of both sides of the equation to extract from inside the tangent.
Step 4.2.3
Simplify the right side.
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Step 4.2.3.1
Evaluate .
Step 4.2.4
The tangent function is negative in the second and fourth quadrants. To find the second solution, subtract the reference angle from to find the solution in the third quadrant.
Step 4.2.5
Simplify the expression to find the second solution.
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Step 4.2.5.1
Add to .
Step 4.2.5.2
The resulting angle of is positive and coterminal with .
Step 4.2.6
Find the period of .
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Step 4.2.6.1
The period of the function can be calculated using .
Step 4.2.6.2
Replace with in the formula for period.
Step 4.2.6.3
The absolute value is the distance between a number and zero. The distance between and is .
Step 4.2.6.4
Divide by .
Step 4.2.7
Add to every negative angle to get positive angles.
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Step 4.2.7.1
Add to to find the positive angle.
Step 4.2.7.2
Subtract from .
Step 4.2.7.3
List the new angles.
Step 4.2.8
The period of the function is so values will repeat every degrees in both directions.
, for any integer
, for any integer
, for any integer
Step 5
The final solution is all the values that make true.
, for any integer
Step 6
Consolidate and to .
, for any integer