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一、连半径构造直角三角形当圆中有垂直于弦的直径时,通常连半径,由半径、弦的一半以及圆心到弦的距离构成直角三角形进行求解.例1 1400年前,我国隋朝建造的赵州石拱桥(如图34-1)是圆弧形,它的跨度(即弧所对的弦长)为37.4 m,拱高(即弧的中点到弦的距离)为7.2 m,求桥拱所在圆的半径(结果精确到0.1 m).
First, with a radius of the construction of right-angled triangle When the circle perpendicular to the diameter of the string, usually with a radius, the radius, the chord half and the distance from the center of the circle to form a right triangle to solve Example 1 1400 years ago, China’s Sui Dynasty Zhaozhou stone arch (Figure 34-1) is circular arc, its span (ie, the chord length of the arc) is 37.4 m, the arch height (ie, the distance from the midpoint of the arc to the chord) is 7.2 m, The radius of the circle where the arch is located (result accurate to 0.1 m).