# Writing a circle equation in standard

Gartneer; Updated April 25, Different geometric shapes have their own distinct equations that aid in their graphing and solution. Sciencing Video Vault Square the radius to finalize the equation. It emerges from a more general formula: Yowza -- we're relating an imaginary exponent to sine and cosine!

## Writing Equations in Standard Form

And somehow plugging in pi gives -1? Could this ever be intuitive? Not according to s mathematician Benjamin Peirce: It is absolutely paradoxical; we cannot understand it, and we don't know what it means, but we have proved it, and therefore we know it must be the truth. Argh, this attitude makes my blood boil!

Formulas are not magical spells to be memorized: Euler's formula describes two equivalent ways to move in a circle. This stunning equation is about spinning around? Yes -- and we can understand it by building on a few analogies: Starting at the number 1, see multiplication as a transformation that changes the number: If they can't think it through, Euler's formula is still a magic spell to them.

While writing, I thought a companion video might help explain the ideas more clearly: It follows the post; watch together, or at your leisure. Euler's formula is the latter: If we examine circular motion using trig, and travel x radians: The analogy "complex numbers are 2-dimensional" helps us interpret a single complex number as a position on a circle.

Now let's figure out how the e side of the equation accomplishes it. What is Imaginary Growth? Combining x- and y- coordinates into a complex number is tricky, but manageable. But what does an imaginary exponent mean? Let's step back a bit. When I see 34, I think of it like this: Regular growth is simple: Imaginary growth is different: It's like a jet engine that was strapped on sideways -- instead of going forward, we start pushing at 90 degrees.

The neat thing about a constant orthogonal perpendicular push is that it doesn't speed you up or slow you down -- it rotates you! Taking any number and multiplying by i will not change its magnitude, just the direction it points.

Intuitively, here's how I see continuous imaginary growth rate: I wondered that too. Regular growth compounds in our original direction, so we go 1, 2, 4, 8, 16, multiplying 2x each time and staying in the real numbers.

We can consider this eln 2xwhich means grow instantly at a rate of ln 2 for "x" seconds. And hey -- if our growth rate was twice as fast, 2ln 2 vs ln 2it would look the same as growing for twice as long 2x vs x. The magic of e lets us swap rate and time; 2 seconds at ln 2 is the same growth as 1 second at 2ln 2.

Now, imagine we have some purely imaginary growth rate Ri that rotates us until we reach i, or 90 degrees upward. What happens if we double that rate to 2Ri, will we spin off the circle? Having a rate of 2Ri means we just spin twice as fast, or alternatively, spin at a rate of R for twice as long, but we're staying on the circle.

Rotating twice as long means we're now facing degrees. Once we realize that some exponential growth rate can take us from 1 to i, increasing that rate just spins us more.

We'll never escape the circle.Circle Equations. A circle is easy to make. Draw a curve that is "radius" away from a central point. And so: All points are the same distance from the center. kcc1 Count to by ones and by tens. kcc2 Count forward beginning from a given number within the known sequence (instead of having to begin at 1).

kcc3 Write numbers from 0 to Represent a number of objects with a written numeral (with 0 representing a count of no objects). kcc4a When counting objects, say the number names in the standard order, pairing each object with one and only. To describe the earth's rotation about its polar axis, we use the concept of the hour angle. As shown in Figure , the hour angle is the angular distance between the meridian of the observer and the meridian whose plane contains the sun.

Not Just Triangles Any More. The trig functions are sometimes called circular functions because they’re intimately associated with circles. You’ve already seen that, with all six functions in a complicated diagram, but let’s reduce it to the essentials. Take a right triangle, and place one of the two acute angles at the center of a circle, with the adjacent leg along the x axis.

Here is a course in boundary element methods for the absolute beginners. It assumes some prior basic knowledge of vector calculus (covering topics such as line, surface and volume integrals and the various integral theorems), ordinary and partial differential equations, . After understanding the exponential function, our next target is the natural logarithm..

Given how the natural log is described in math books, there’s little “natural” about it: it’s defined as the inverse of e^x, a strange enough exponent already.

Circle equation calculator - with detailed explanation