P is the vertical line of XOY plane, the vertical foot is Q, and Q is OX; The vertical line and vertical foot of OY are m and n, respectively;

To connect OQ, let PM=7 and PN=3, so OQ=4.

It is easy to know that OMPN is rectangular, so MN=4.

Om 2+MQ = 4 2 = 16 = OQ 2、

pq^2+mq^2=mp^2=49,pq^2+nq^2=pn^2=9，

So 2 * pq2 = 49-mq2+9-nq2 = 58-(om 2+MQ) = 42.

PQ^2=2 1

And op2 = oq2+pq2 =16+21= 37.

OP= root number 37