Trigonometry Examples

Solve for x tan(x)=8/5
tan(x)=85
Step 1
Take the inverse tangent of both sides of the equation to extract x from inside the tangent.
x=arctan(85)
Step 2
Simplify the right side.
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Step 2.1
Evaluate arctan(85).
x=1.01219701
x=1.01219701
Step 3
The tangent function is positive in the first and third quadrants. To find the second solution, add the reference angle from π to find the solution in the fourth quadrant.
x=(3.14159265)+1.01219701
Step 4
Solve for x.
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Step 4.1
Remove parentheses.
x=3.14159265+1.01219701
Step 4.2
Remove parentheses.
x=(3.14159265)+1.01219701
Step 4.3
Add 3.14159265 and 1.01219701.
x=4.15378966
x=4.15378966
Step 5
Find the period of tan(x).
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Step 5.1
The period of the function can be calculated using π|b|.
π|b|
Step 5.2
Replace b with 1 in the formula for period.
π|1|
Step 5.3
The absolute value is the distance between a number and zero. The distance between 0 and 1 is 1.
π1
Step 5.4
Divide π by 1.
π
π
Step 6
The period of the tan(x) function is π so values will repeat every π radians in both directions.
x=1.01219701+πn,4.15378966+πn, for any integer n
Step 7
Consolidate 1.01219701+πn and 4.15378966+πn to 1.01219701+πn.
x=1.01219701+πn, for any integer n
tan(x)=85
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