Trigonometry Examples

Find Trig Functions Using Identities tan(theta)=-8/15 , cos(theta)<0
,
Step 1
The cosine function is negative in the second and third quadrants. The tangent function is negative in the second and fourth quadrants. The set of solutions for are limited to the second quadrant since that is the only quadrant found in both sets.
Solution is in the second quadrant.
Step 2
Use the definition of tangent to find the known sides of the unit circle right triangle. The quadrant determines the sign on each of the values.
Step 3
Find the hypotenuse of the unit circle triangle. Since the opposite and adjacent sides are known, use the Pythagorean theorem to find the remaining side.
Step 4
Replace the known values in the equation.
Step 5
Simplify inside the radical.
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Step 5.1
Raise to the power of .
Hypotenuse
Step 5.2
Raise to the power of .
Hypotenuse
Step 5.3
Add and .
Hypotenuse
Step 5.4
Rewrite as .
Hypotenuse
Step 5.5
Pull terms out from under the radical, assuming positive real numbers.
Hypotenuse
Hypotenuse
Step 6
Find the value of sine.
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Step 6.1
Use the definition of sine to find the value of .
Step 6.2
Substitute in the known values.
Step 7
Find the value of cosine.
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Step 7.1
Use the definition of cosine to find the value of .
Step 7.2
Substitute in the known values.
Step 7.3
Move the negative in front of the fraction.
Step 8
Find the value of cotangent.
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Step 8.1
Use the definition of cotangent to find the value of .
Step 8.2
Substitute in the known values.
Step 8.3
Move the negative in front of the fraction.
Step 9
Find the value of secant.
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Step 9.1
Use the definition of secant to find the value of .
Step 9.2
Substitute in the known values.
Step 9.3
Move the negative in front of the fraction.
Step 10
Find the value of cosecant.
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Step 10.1
Use the definition of cosecant to find the value of .
Step 10.2
Substitute in the known values.
Step 11
This is the solution to each trig value.