Tag: measurement curved LED billboard, calculation method of arc LED display screen
1. Please measure out chord length，chord height and arc length. In general, the dimension of arc length is hard to measure out and it also exist large size differences. Therefore, we often compute arc length or radius according to chord height and chord length. The difference value allowed within 10cm more or less. If the value was over 10cm, it should be measured or computed repeatedly.


2. The measuring method of chord length & height: chord length is the straightline distance from two endpoints of the arc. The midpoint of length to midpoint of curved lines is chord height.
3. The method of computing arc length and radius: figuring out the degrees of triangle framed by chord length & height.
For example:
a. Supposing the chord height as b and chord length as 2a=100, b=60.


b. The triangle is made by chord height and length, therefore the side length are a=100, b=60.


c. According to Pythagorean Theorem, we can compute the third side length C=116.62 (that is a2 + b2 = c2).
d. Then according to trigonometric formulas: sin∠A=a/c(∠A is opposite angle of diagonal al), thus, sin∠A=0.86 and compute the arcsine∠A=59.32°


e. Drawing Side b to the center of the stretch , ∠ B vertex to the center of the connection and then form an isosceles triangle. According to the theory that interior angles of a triangle and 180 °, we concluded that∠C=62°and the curved billboard radians is 124 °.


f. In line with sin∠C=c/ bevel edge, we concluded sin62=100/ bevel edge. We can calculate sin62=0.883, thus the bevel edge=113.3.


g. The circumference of arc is : 2πR=2*3.14*113.3 =711.52. circumference/ 360= 1.98, The arc length= 1.98*billboard radian124°=245.52
Final results are: arc length=245.52, radian=124°, R=113.3