Trigonometry Examples

Find the Exact Value (2tan((5pi)/8))/(1-tan((5pi)/8)^2)
Step 1
Simplify the numerator.
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Step 1.1
The exact value of is .
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Step 1.1.1
Rewrite as an angle where the values of the six trigonometric functions are known divided by .
Step 1.1.2
Apply the tangent half-angle identity.
Step 1.1.3
Change the to because tangent is negative in the second quadrant.
Step 1.1.4
Simplify .
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Step 1.1.4.1
Apply the reference angle by finding the angle with equivalent trig values in the first quadrant. Make the expression negative because cosine is negative in the third quadrant.
Step 1.1.4.2
The exact value of is .
Step 1.1.4.3
Multiply .
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Step 1.1.4.3.1
Multiply by .
Step 1.1.4.3.2
Multiply by .
Step 1.1.4.4
Write as a fraction with a common denominator.
Step 1.1.4.5
Combine the numerators over the common denominator.
Step 1.1.4.6
Apply the reference angle by finding the angle with equivalent trig values in the first quadrant. Make the expression negative because cosine is negative in the third quadrant.
Step 1.1.4.7
The exact value of is .
Step 1.1.4.8
Write as a fraction with a common denominator.
Step 1.1.4.9
Combine the numerators over the common denominator.
Step 1.1.4.10
Multiply the numerator by the reciprocal of the denominator.
Step 1.1.4.11
Cancel the common factor of .
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Step 1.1.4.11.1
Cancel the common factor.
Step 1.1.4.11.2
Rewrite the expression.
Step 1.1.4.12
Multiply by .
Step 1.1.4.13
Multiply by .
Step 1.1.4.14
Expand the denominator using the FOIL method.
Step 1.1.4.15
Simplify.
Step 1.1.4.16
Apply the distributive property.
Step 1.1.4.17
Cancel the common factor of .
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Step 1.1.4.17.1
Cancel the common factor.
Step 1.1.4.17.2
Rewrite the expression.
Step 1.1.4.18
Combine and .
Step 1.1.4.19
Simplify each term.
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Step 1.1.4.19.1
Apply the distributive property.
Step 1.1.4.19.2
Move to the left of .
Step 1.1.4.19.3
Combine using the product rule for radicals.
Step 1.1.4.19.4
Simplify each term.
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Step 1.1.4.19.4.1
Multiply by .
Step 1.1.4.19.4.2
Rewrite as .
Step 1.1.4.19.4.3
Pull terms out from under the radical, assuming positive real numbers.
Step 1.1.4.19.5
Cancel the common factor of and .
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Step 1.1.4.19.5.1
Factor out of .
Step 1.1.4.19.5.2
Factor out of .
Step 1.1.4.19.5.3
Factor out of .
Step 1.1.4.19.5.4
Cancel the common factors.
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Step 1.1.4.19.5.4.1
Factor out of .
Step 1.1.4.19.5.4.2
Cancel the common factor.
Step 1.1.4.19.5.4.3
Rewrite the expression.
Step 1.1.4.19.5.4.4
Divide by .
Step 1.1.4.20
Add and .
Step 1.1.4.21
Add and .
Step 1.2
Combine exponents.
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Step 1.2.1
Factor out negative.
Step 1.2.2
Multiply by .
Step 2
Simplify the denominator.
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Step 2.1
Rewrite as .
Step 2.2
Since both terms are perfect squares, factor using the difference of squares formula, where and .
Step 2.3
Simplify.
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Step 2.3.1
The exact value of is .
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Step 2.3.1.1
Rewrite as an angle where the values of the six trigonometric functions are known divided by .
Step 2.3.1.2
Apply the tangent half-angle identity.
Step 2.3.1.3
Change the to because tangent is negative in the second quadrant.
Step 2.3.1.4
Simplify .
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Step 2.3.1.4.1
Apply the reference angle by finding the angle with equivalent trig values in the first quadrant. Make the expression negative because cosine is negative in the third quadrant.
Step 2.3.1.4.2
The exact value of is .
Step 2.3.1.4.3
Multiply .
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Step 2.3.1.4.3.1
Multiply by .
Step 2.3.1.4.3.2
Multiply by .
Step 2.3.1.4.4
Write as a fraction with a common denominator.
Step 2.3.1.4.5
Combine the numerators over the common denominator.
Step 2.3.1.4.6
Apply the reference angle by finding the angle with equivalent trig values in the first quadrant. Make the expression negative because cosine is negative in the third quadrant.
Step 2.3.1.4.7
The exact value of is .
Step 2.3.1.4.8
Write as a fraction with a common denominator.
Step 2.3.1.4.9
Combine the numerators over the common denominator.
Step 2.3.1.4.10
Multiply the numerator by the reciprocal of the denominator.
Step 2.3.1.4.11
Cancel the common factor of .
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Step 2.3.1.4.11.1
Cancel the common factor.
Step 2.3.1.4.11.2
Rewrite the expression.
Step 2.3.1.4.12
Multiply by .
Step 2.3.1.4.13
Multiply by .
Step 2.3.1.4.14
Expand the denominator using the FOIL method.
Step 2.3.1.4.15
Simplify.
Step 2.3.1.4.16
Apply the distributive property.
Step 2.3.1.4.17
Cancel the common factor of .
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Step 2.3.1.4.17.1
Cancel the common factor.
Step 2.3.1.4.17.2
Rewrite the expression.
Step 2.3.1.4.18
Combine and .
Step 2.3.1.4.19
Simplify each term.
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Step 2.3.1.4.19.1
Apply the distributive property.
Step 2.3.1.4.19.2
Move to the left of .
Step 2.3.1.4.19.3
Combine using the product rule for radicals.
Step 2.3.1.4.19.4
Simplify each term.
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Step 2.3.1.4.19.4.1
Multiply by .
Step 2.3.1.4.19.4.2
Rewrite as .
Step 2.3.1.4.19.4.3
Pull terms out from under the radical, assuming positive real numbers.
Step 2.3.1.4.19.5
Cancel the common factor of and .
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Step 2.3.1.4.19.5.1
Factor out of .
Step 2.3.1.4.19.5.2
Factor out of .
Step 2.3.1.4.19.5.3
Factor out of .
Step 2.3.1.4.19.5.4
Cancel the common factors.
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Step 2.3.1.4.19.5.4.1
Factor out of .
Step 2.3.1.4.19.5.4.2
Cancel the common factor.
Step 2.3.1.4.19.5.4.3
Rewrite the expression.
Step 2.3.1.4.19.5.4.4
Divide by .
Step 2.3.1.4.20
Add and .
Step 2.3.1.4.21
Add and .
Step 2.3.2
The exact value of is .
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Step 2.3.2.1
Rewrite as an angle where the values of the six trigonometric functions are known divided by .
Step 2.3.2.2
Apply the tangent half-angle identity.
Step 2.3.2.3
Change the to because tangent is negative in the second quadrant.
Step 2.3.2.4
Simplify .
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Step 2.3.2.4.1
Apply the reference angle by finding the angle with equivalent trig values in the first quadrant. Make the expression negative because cosine is negative in the third quadrant.
Step 2.3.2.4.2
The exact value of is .
Step 2.3.2.4.3
Multiply .
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Step 2.3.2.4.3.1
Multiply by .
Step 2.3.2.4.3.2
Multiply by .
Step 2.3.2.4.4
Write as a fraction with a common denominator.
Step 2.3.2.4.5
Combine the numerators over the common denominator.
Step 2.3.2.4.6
Apply the reference angle by finding the angle with equivalent trig values in the first quadrant. Make the expression negative because cosine is negative in the third quadrant.
Step 2.3.2.4.7
The exact value of is .
Step 2.3.2.4.8
Write as a fraction with a common denominator.
Step 2.3.2.4.9
Combine the numerators over the common denominator.
Step 2.3.2.4.10
Multiply the numerator by the reciprocal of the denominator.
Step 2.3.2.4.11
Cancel the common factor of .
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Step 2.3.2.4.11.1
Cancel the common factor.
Step 2.3.2.4.11.2
Rewrite the expression.
Step 2.3.2.4.12
Multiply by .
Step 2.3.2.4.13
Multiply by .
Step 2.3.2.4.14
Expand the denominator using the FOIL method.
Step 2.3.2.4.15
Simplify.
Step 2.3.2.4.16
Apply the distributive property.
Step 2.3.2.4.17
Cancel the common factor of .
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Step 2.3.2.4.17.1
Cancel the common factor.
Step 2.3.2.4.17.2
Rewrite the expression.
Step 2.3.2.4.18
Combine and .
Step 2.3.2.4.19
Simplify each term.
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Step 2.3.2.4.19.1
Apply the distributive property.
Step 2.3.2.4.19.2
Move to the left of .
Step 2.3.2.4.19.3
Combine using the product rule for radicals.
Step 2.3.2.4.19.4
Simplify each term.
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Step 2.3.2.4.19.4.1
Multiply by .
Step 2.3.2.4.19.4.2
Rewrite as .
Step 2.3.2.4.19.4.3
Pull terms out from under the radical, assuming positive real numbers.
Step 2.3.2.4.19.5
Cancel the common factor of and .
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Step 2.3.2.4.19.5.1
Factor out of .
Step 2.3.2.4.19.5.2
Factor out of .
Step 2.3.2.4.19.5.3
Factor out of .
Step 2.3.2.4.19.5.4
Cancel the common factors.
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Step 2.3.2.4.19.5.4.1
Factor out of .
Step 2.3.2.4.19.5.4.2
Cancel the common factor.
Step 2.3.2.4.19.5.4.3
Rewrite the expression.
Step 2.3.2.4.19.5.4.4
Divide by .
Step 2.3.2.4.20
Add and .
Step 2.3.2.4.21
Add and .
Step 2.3.3
Multiply .
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Step 2.3.3.1
Multiply by .
Step 2.3.3.2
Multiply by .
Step 3
Expand using the FOIL Method.
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Step 3.1
Apply the distributive property.
Step 3.2
Apply the distributive property.
Step 3.3
Apply the distributive property.
Step 4
Simplify and combine like terms.
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Step 4.1
Simplify each term.
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Step 4.1.1
Multiply by .
Step 4.1.2
Multiply by .
Step 4.1.3
Multiply by .
Step 4.1.4
Multiply .
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Step 4.1.4.1
Raise to the power of .
Step 4.1.4.2
Raise to the power of .
Step 4.1.4.3
Use the power rule to combine exponents.
Step 4.1.4.4
Add and .
Step 4.1.5
Rewrite as .
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Step 4.1.5.1
Use to rewrite as .
Step 4.1.5.2
Apply the power rule and multiply exponents, .
Step 4.1.5.3
Combine and .
Step 4.1.5.4
Cancel the common factor of .
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Step 4.1.5.4.1
Cancel the common factor.
Step 4.1.5.4.2
Rewrite the expression.
Step 4.1.5.5
Simplify.
Step 4.1.6
Apply the distributive property.
Step 4.1.7
Multiply by .
Step 4.1.8
Multiply by .
Step 4.2
Subtract from .
Step 4.3
Subtract from .
Step 4.4
Add and .
Step 5
Cancel the common factor of and .
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Step 5.1
Factor out of .
Step 5.2
Cancel the common factors.
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Step 5.2.1
Factor out of .
Step 5.2.2
Factor out of .
Step 5.2.3
Factor out of .
Step 5.2.4
Cancel the common factor.
Step 5.2.5
Rewrite the expression.
Step 6
Move the negative in front of the fraction.
Step 7
Multiply by .
Step 8
Simplify terms.
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Step 8.1
Multiply by .
Step 8.2
Expand the denominator using the FOIL method.
Step 8.3
Simplify.
Step 8.4
Simplify the expression.
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Step 8.4.1
Move the negative one from the denominator of .
Step 8.4.2
Rewrite as .
Step 8.5
Apply the distributive property.
Step 8.6
Move to the left of .
Step 8.7
Combine using the product rule for radicals.
Step 9
Rewrite as .
Step 10
Apply the distributive property.
Step 11
Multiply .
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Step 11.1
Multiply by .
Step 11.2
Multiply by .
Step 12
Apply the distributive property.
Step 13
Multiply .
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Step 13.1
Multiply by .
Step 13.2
Multiply by .
Step 14
The result can be shown in multiple forms.
Exact Form:
Decimal Form: