1.
(2024九下·中山模拟)
如图,美术素描课堂上有很多关于黄金分割比的元素,比如脸部素描就需要考虑黄金分割比的问题,按照如下要求作出的人脸图像比较美观:(1)眉头、眼头、鼻翼在一条竖直直线上;(2)眉头和眉峰的水平距离(图中直线①和直线②的距离)和眼长大致相等(设此长度为a),眉头和眉尾的水平距离(图中直线①和直线③的距离)设为b,a与b的比例为黄金分割比
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmfrac%3E%3Cmrow%3E%3Cmsqrt%3E%3Cmn%3E5%3C%2Fmn%3E%3C%2Fmsqrt%3E%3Cmo%3E%E2%88%92%3C%2Fmo%3E%3Cmn%3E1%3C%2Fmn%3E%3C%2Fmrow%3E%3Cmn%3E2%3C%2Fmn%3E%3C%2Fmfrac%3E%3C%2Fmrow%3E%3C%2Fmath%3E)
;(3)眉尾、眼梢、鼻翼在同一直线上.某同学按照以上要求进行素描,已知他的素描作品中眼梢到眉尾的距离为
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmtext%3E2cm%3C%2Fmtext%3E%3C%2Fmrow%3E%3C%2Fmath%3E)
, 则眼梢到鼻翼的距离为
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmtext%3Ecm%3C%2Fmtext%3E%3C%2Fmrow%3E%3C%2Fmath%3E)
. (
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmsqrt%3E%3Cmn%3E5%3C%2Fmn%3E%3C%2Fmsqrt%3E%3Cmo%3E%E2%89%88%3C%2Fmo%3E%3Cmn%3E2.236%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmath%3E)
, 结果保留两位小数)
![](//tikupic.21cnjy.com/1024/2024/06/17/85/b1/85b174fda90098ee00af6eff600f4212_222x206.png)