A normal human being can rotate his neck at maximum angle of 70 degree at one stretch
So here the maximum angle is 70 degree upto which he can see the height
now we will have
![tan\theta = (H)/(d)](https://img.qammunity.org/2019/formulas/physics/college/7n21c1a4f2ebn7ds56hr4iqng5xwp8m1he.png)
![tan70 = (227.4 - 4.3)/(d)](https://img.qammunity.org/2019/formulas/physics/college/khhkw8d1cwpxhcd4kppoe6p9dam3rr1asd.png)
now we have
![d = 81.2 m](https://img.qammunity.org/2019/formulas/physics/college/voqsytrwmbu8bytpocof8zpdrzvhqcp7zo.png)
so he is able to see the top at minimum distance of 81.2 m from that gate