The answer is easier if angles are measured in radians. At the end, you'll get a conversion from radians to degrees.
You are given a circle with diameter d, and a chord that subtends an arc of length x. Let c be the length of the chord and write r = d/2 for the radius of the circle.
The arc subtends an angle of y = x/r radians at the centre of the circle.
(If you draw a chord and the perpendicular from the centre of the circle to the midpoint of the chord, the following trigonometry is easier to understand).
sin(y) = (c/2)/r where c is the length of the chord.
so sin(y) = c/2r
and so c = 2r*sin(y) = d*sin(y) = d*sin(x/r) = d*sin(x/2d)
Everything on the right hand side is known and so c is easily calculated.
Radians-degrees
A whole circle is 360 degrees of 2*pi radians so 1 radian = 180/pi degrees. Writing 180/pi each time is tedious and also, higher maths is all in radians anyway, so I tend to avoid working with degrees. If you are using this on a calculator, make sure the angles are being measured in radians. The default units for angles in Excel is radians.
The longest chord in a circle is its diameter and halve of this is its radius.
all you have to do is find a line with two endpoints on the circle also a diameter is the longest chord on a circle that runs through the middle of the circle.
Divide the diameter by 2.
Unless the chord is the diameter, there is no way to measure the radius of the circle. This is because the radius is in no way dependent on chord length since circles have infinite amount of chord lengths.
a diameter
The longest chord in a circle is its diameter and halve of this is its radius.
If you are given a chord length of a circle, unless you are given more information about the chord, you can not determine what the radius of the circle will be. This is because the chord length in a circle can vary from a length of (essentially) 0, up to a length of double the radius (the diameter). The best you can say about the radius if given the chord length, is that the length of the radius is at least as long has half half the chord length.
all you have to do is find a line with two endpoints on the circle also a diameter is the longest chord on a circle that runs through the middle of the circle.
It'll be the largest chord of the circle.
A chord - is a straight-line joining two points on the circumference. The longest chord is the diameter.
Diameter of a circle = circumference/pi
Divide the diameter by 2.
The diameter of a circle is simply twice the radius. It is the length of a chord running thru the center point of the circle. Can also be found by taking the circumference and dividing it by pi.
Unless the chord is the diameter, there is no way to measure the radius of the circle. This is because the radius is in no way dependent on chord length since circles have infinite amount of chord lengths.
If the area of a circle is given as 67cm squared, the diameter is 9.236 cm and the circumference is 29.02 cm
a diameter
There are an infinite number of possible chords in anycircle, regardless of its diameter. A chord is a line segment with its endpoints on the curve (circumference) of the circle. You can draw those all day and never draw the same one twice.