Trigonometry Examples

Find the Focus y^2=-20x
Step 1
Rewrite the equation in vertex form.
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Step 1.1
Isolate to the left side of the equation.
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Step 1.1.1
Rewrite the equation as .
Step 1.1.2
Divide each term in by and simplify.
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Step 1.1.2.1
Divide each term in by .
Step 1.1.2.2
Simplify the left side.
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Step 1.1.2.2.1
Cancel the common factor of .
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Step 1.1.2.2.1.1
Cancel the common factor.
Step 1.1.2.2.1.2
Divide by .
Step 1.1.2.3
Simplify the right side.
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Step 1.1.2.3.1
Move the negative in front of the fraction.
Step 1.2
Complete the square for .
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Step 1.2.1
Use the form , to find the values of , , and .
Step 1.2.2
Consider the vertex form of a parabola.
Step 1.2.3
Find the value of using the formula .
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Step 1.2.3.1
Substitute the values of and into the formula .
Step 1.2.3.2
Simplify the right side.
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Step 1.2.3.2.1
Cancel the common factor of and .
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Step 1.2.3.2.1.1
Factor out of .
Step 1.2.3.2.1.2
Cancel the common factors.
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Step 1.2.3.2.1.2.1
Cancel the common factor.
Step 1.2.3.2.1.2.2
Rewrite the expression.
Step 1.2.3.2.2
Multiply the numerator by the reciprocal of the denominator.
Step 1.2.3.2.3
Multiply .
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Step 1.2.3.2.3.1
Multiply by .
Step 1.2.3.2.3.2
Multiply by .
Step 1.2.4
Find the value of using the formula .
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Step 1.2.4.1
Substitute the values of , and into the formula .
Step 1.2.4.2
Simplify the right side.
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Step 1.2.4.2.1
Simplify each term.
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Step 1.2.4.2.1.1
Raising to any positive power yields .
Step 1.2.4.2.1.2
Simplify the denominator.
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Step 1.2.4.2.1.2.1
Multiply by .
Step 1.2.4.2.1.2.2
Combine and .
Step 1.2.4.2.1.3
Reduce the expression by cancelling the common factors.
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Step 1.2.4.2.1.3.1
Cancel the common factor of and .
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Step 1.2.4.2.1.3.1.1
Factor out of .
Step 1.2.4.2.1.3.1.2
Cancel the common factors.
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Step 1.2.4.2.1.3.1.2.1
Factor out of .
Step 1.2.4.2.1.3.1.2.2
Cancel the common factor.
Step 1.2.4.2.1.3.1.2.3
Rewrite the expression.
Step 1.2.4.2.1.3.2
Move the negative in front of the fraction.
Step 1.2.4.2.1.4
Multiply the numerator by the reciprocal of the denominator.
Step 1.2.4.2.1.5
Multiply .
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Step 1.2.4.2.1.5.1
Multiply by .
Step 1.2.4.2.1.5.2
Multiply by .
Step 1.2.4.2.1.5.3
Multiply by .
Step 1.2.4.2.2
Add and .
Step 1.2.5
Substitute the values of , , and into the vertex form .
Step 1.3
Set equal to the new right side.
Step 2
Use the vertex form, , to determine the values of , , and .
Step 3
Find the vertex .
Step 4
Find , the distance from the vertex to the focus.
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Step 4.1
Find the distance from the vertex to a focus of the parabola by using the following formula.
Step 4.2
Substitute the value of into the formula.
Step 4.3
Simplify.
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Step 4.3.1
Cancel the common factor of and .
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Step 4.3.1.1
Rewrite as .
Step 4.3.1.2
Move the negative in front of the fraction.
Step 4.3.2
Combine and .
Step 4.3.3
Cancel the common factor of and .
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Step 4.3.3.1
Factor out of .
Step 4.3.3.2
Cancel the common factors.
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Step 4.3.3.2.1
Factor out of .
Step 4.3.3.2.2
Cancel the common factor.
Step 4.3.3.2.3
Rewrite the expression.
Step 4.3.4
Multiply the numerator by the reciprocal of the denominator.
Step 4.3.5
Multiply .
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Step 4.3.5.1
Multiply by .
Step 4.3.5.2
Multiply by .
Step 5
Find the focus.
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Step 5.1
The focus of a parabola can be found by adding to the x-coordinate if the parabola opens left or right.
Step 5.2
Substitute the known values of , , and into the formula and simplify.
Step 6