Is a diameter a chord?

A chord that passes through the center of a circle is called a diameter and is the longest chord of that specific circle.

en.wikipedia.org - Chord (geometry) - Wikipedia

What is a 2u key?

Remember these: 2u keycap is Backspace. 2.25u keycap is Left Shift or Enter. 2.75u is Right Shift. Apr 19, 2021

Last updated Jun 1, 2018

What can I polish my piano with?

Use a high-quality piano polish that doesn't contain alcohol or silicone. Ideally, find a high-gloss polish that can be used on plastic as they are...

Last updated Jul 26, 2018

Join almost HALF A MILLION Happy Students Worldwide

Pianoforall is one of the most popular online piano courses online and has helped over 450,000 students around the world achieve their dream of playing beautiful piano for over a decade.

Learn More »

Promotion

Geometric line segment whose endpoints both lie on the curve

This article is about the line segment defined on a curve. For other uses, see Chord (disambiguation) A chord of a circle is a straight line segment whose endpoints both lie on a circular arc. The infinite line extension of a chord is a secant line, or just secant. More generally, a chord is a line segment joining two points on any curve, for instance, an ellipse. A chord that passes through a circle's center point is the circle's diameter. The word chord is from the Latin chorda meaning bowstring.

BX is a chord

(as is the diameter segment AB). The red segmentis a(as is the diameter segment).

In circles [ edit ]

Among properties of chords of a circle are the following:

Chords are equidistant from the center if and only if their lengths are equal. Equal chords are subtended by equal angles from the center of the circle. A chord that passes through the center of a circle is called a diameter and is the longest chord of that specific circle. If the line extensions (secant lines) of chords AB and CD intersect at a point P, then their lengths satisfy AP·PB = CP·PD (power of a point theorem).

In conics [ edit ]

The midpoints of a set of parallel chords of a conic are collinear (midpoint theorem for conics).[1]

In trigonometry [ edit ]

Chords were used extensively in the early development of trigonometry. The first known trigonometric table, compiled by Hipparchus, tabulated the value of the chord function for every 7+1/2 degrees. In the second century AD, Ptolemy of Alexandria compiled a more extensive table of chords in his book on astronomy, giving the value of the chord for angles ranging from 1/2 to 180 degrees by increments of 1/2 degree. The circle was of diameter 120, and the chord lengths are accurate to two base-60 digits after the integer part.[2] The chord function is defined geometrically as shown in the picture. The chord of an angle is the length of the chord between two points on a unit circle separated by that central angle. The angle θ is taken in the positive sense and must lie in the interval 0 < θ ≤ π (radian measure). The chord function can be related to the modern sine function, by taking one of the points to be (1,0), and the other point to be (cos θ, sin θ), and then using the Pythagorean theorem to calculate the chord length:[2] crd ⁡ θ = ( 1 − cos ⁡ θ ) 2 + sin 2 ⁡ θ = 2 − 2 cos ⁡ θ = 2 sin ⁡ ( θ 2 ) . {displaystyle operatorname {crd} heta ={sqrt {(1-cos heta )^{2}+sin ^{2} heta }}={sqrt {2-2cos heta }}=2sin left({frac { heta }{2}} ight).}

Is your lunch break included in working hours?

Working lunches and rest breaks You should leave out any lunch breaks where you don't have to do any work. You should also leave out any lunch...

Last updated Jun 16, 2019

Do singers live longer?

Among conductors, the difference was 2.4 years for men and 9.9 years for women; male opera singers lived 5.3 years more and female opera singers...

Last updated Mar 23, 2022

Promotion

The last step uses the half-angle formula. Much as modern trigonometry is built on the sine function, ancient trigonometry was built on the chord function. Hipparchus is purported to have written a twelve-volume work on chords, all now lost, so presumably, a great deal was known about them. In the table below (where c is the chord length, and D the diameter of the circle) the chord function can be shown to satisfy many identities analogous to well-known modern ones: Name Sine-based Chord-based Pythagorean sin 2 ⁡ θ + cos 2 ⁡ θ = 1 {displaystyle sin ^{2} heta +cos ^{2} heta =1,} crd 2 ⁡ θ + crd 2 ⁡ ( π − θ ) = 4 {displaystyle operatorname {crd} ^{2} heta +operatorname {crd} ^{2}(pi - heta )=4,} Half-angle sin ⁡ θ 2 = ± 1 − cos ⁡ θ 2 {displaystyle sin {frac { heta }{2}}=pm {sqrt {frac {1-cos heta }{2}}},} crd ⁡ θ 2 = 2 − crd ⁡ ( π − θ ) {displaystyle operatorname {crd} {frac { heta }{2}}={sqrt {2-operatorname {crd} (pi - heta )}},} Apothem (a) c = 2 r 2 − a 2 {displaystyle c=2{sqrt {r^{2}-a^{2}}}} c = D 2 − 4 a 2 {displaystyle c={sqrt {D^{2}-4a^{2}}}} Angle (θ) c = 2 r sin ⁡ ( θ 2 ) {displaystyle c=2rsin left({frac { heta }{2}} ight)} c = D 2 crd ⁡ θ {displaystyle c={frac {D}{2}}operatorname {crd} heta }

The inverse function exists as well:[3]

θ = 2 arcsin ⁡ c 2 r {displaystyle heta =2arcsin {frac {c}{2r}}}

References [ edit ]

en.wikipedia.org - Chord (geometry) - Wikipedia

Can I learn piano on Android?

Simply piano is available for both iOS and Android devices as an app that contains everything you need to learn piano. It works by using the...

Last updated Nov 26, 2018

Did Kurt Cobain smash guitars?

on July 9. It was the latter appearance where Cobain smashed the guitar to pieces across the stage during the finale performance of "Blew." Nov 14,...

Last updated Jun 8, 2019