Question

已知弦长3.2米,弦高0.4米求弧长是多少,急,

Answer 1

已知弦长L=3.2米,弦高H=0.4米求弧长C是多少?

R^2=(R-H)^2+(L/2)^2

R^2=R^2-2*R*H+H^2+L^2/4

2*R*H=H^2+L^2/4

R=H/2+L^2/(8*H)

=0.4/2+3.2^2/(8*0.4)

=3.4米

A=2*ARC SIN((L/2)/R)

=2*ARC SIN((3.2/2)/3.4)

=56.145度

=56.145*PI/180

=0.97991弧度

C=A*R

=0.97991*3.4

=3.332米