根号下｛1- [(2根号2+根号3）/6]²｝=根号{[36 - (2根号2+根号3)²]/36}=(1/6)*根号[36 -(8+4根号6 +3）】=(1/6)*根号(25 - 4根号6）=(1/6)*根号[(2根号6)² - 2*2根号6 +1²]=(1/6)*根号[(2根号6 -1)²]=(2根号6 -1)/6
